Merge branch 'main' into dev/potc

docs/source/api_doc/tree/common.rst

@@ -36,3 +36,46 @@ RawWrapper
 .. autoclass:: RawWrapper
     :members: __init__, value
 
+
+.. _apidoc_tree_common_delayed_partial:
+
+delayed_partial
+----------------------
+
+.. autofunction:: delayed_partial
+
+
+.. _apidoc_tree_common_undelay:
+
+undelay
+---------------
+
+.. autofunction:: undelay
+
+
+.. _apidoc_tree_common_delayedproxy:
+
+DelayedProxy
+-------------------
+
+.. autoclass:: DelayedProxy
+    :members: value, fvalue
+
+
+.. _apidoc_tree_common_delayedvalueproxy:
+
+DelayedValueProxy
+-------------------
+
+.. autoclass:: DelayedValueProxy
+    :members: __cinit__, value, fvalue
+
+
+.. _apidoc_tree_common_delayedfuncproxy:
+
+DelayedFuncProxy
+-------------------
+
+.. autoclass:: DelayedFuncProxy
+    :members: __cinit__, value, fvalue
+

docs/source/api_doc/tree/tree.rst

@@ -12,6 +12,14 @@ TreeValue
     :members: __init__, __getattribute__, __setattr__, __delattr__, __contains__, __repr__, __iter__, __hash__, __eq__, _attr_extern, __len__, __bool__, __str__, __getstate__, __setstate__, get
 
 
+.. _apidoc_tree_tree_delayed:
+
+delayed
+---------------
+
+.. autofunction:: delayed
+
+
 .. _apidoc_tree_tree_jsonify:
 
 jsonify

requirements-doc.txt

@@ -2,7 +2,7 @@ sphinx~=3.2.0
 sphinx_rtd_theme~=0.4.3
 enum_tools
 sphinx-toolbox
-plantumlcli>=0.0.2
+plantumlcli>=0.0.4
 packaging
 sphinx-multiversion~=0.2.4
 where~=1.0.2

test/tree/common/test_delay.py

+import pytest
+
+from treevalue.tree.common import DelayedProxy, delayed_partial
+
+
+@pytest.mark.unittest
+class TestTreeDelay:
+    def test_delayed_partial_simple(self):
+        cnt = 0
+
+        def f():
+            nonlocal cnt
+            cnt += 1
+            return 1
+
+        pv = delayed_partial(f)
+        assert cnt == 0
+        assert isinstance(pv, DelayedProxy)
+
+        assert pv.value() == 1
+        assert cnt == 1
+
+        assert pv.value() == 1
+        assert cnt == 1
+
+    def test_delayed_partial_func(self):
+        cnt = 0
+
+        def f(x, y):
+            nonlocal cnt
+            cnt += 1
+            return x + y * 2 + 1
+
+        pv = delayed_partial(f, 2, y=3)
+        assert cnt == 0
+        assert isinstance(pv, DelayedProxy)
+
+        assert pv.value() == 9
+        assert cnt == 1
+
+        assert pv.value() == 9
+        assert cnt == 1
+
+    def test_delayed_partial_complex(self):
+        cnt1, cnt2 = 0, 0
+
+        def f1():
+            nonlocal cnt1
+            cnt1 += 1
+            return 1
+
+        def f2(x, y):
+            nonlocal cnt2
+            cnt2 += 1
+            return (x + 1) ** 2 + y + 2
+
+        pv = delayed_partial(f2, delayed_partial(f1), delayed_partial(f1))
+        assert cnt1 == 0
+        assert cnt2 == 0
+        assert isinstance(pv, DelayedProxy)
+
+        assert pv.value() == 7
+        assert cnt1 == 2
+        assert cnt2 == 1
+
+        assert pv.value() == 7
+        assert cnt1 == 2
+        assert cnt2 == 1

test/tree/common/test_storage.py

@@ -2,10 +2,10 @@ import pickle
 
 import pytest
 
-from treevalue.tree.common import create_storage, raw, TreeStorage
+from treevalue.tree.common import create_storage, raw, TreeStorage, delayed_partial
 
 
-# noinspection PyArgumentList,DuplicatedCode
+# noinspection PyArgumentList,DuplicatedCode,PyTypeChecker
 @pytest.mark.unittest
 class TestTreeStorage:
     def test_init(self):
@@ -23,6 +23,52 @@ class TestTreeStorage:
         with pytest.raises(KeyError):
             _ = t.get('fff')
 
+        cnt1, cnt2, cnt3 = 0, 0, 0
+
+        def f1():
+            nonlocal cnt1
+            cnt1 += 1
+            return 2
+
+        def f2(x, y):
+            nonlocal cnt2
+            cnt2 += 1
+            return {'x': x, 'y': y}
+
+        def f3(x, y):
+            nonlocal cnt3
+            cnt3 += 1
+            return create_storage({'x': x, 'y': raw(y)})
+
+        t2 = create_storage({
+            'a': 1,
+            'b': delayed_partial(f1),
+            'c': delayed_partial(f2, delayed_partial(f1), 3),
+            'd': delayed_partial(f3, 3, delayed_partial(f2, 3, 4))
+        })
+
+        assert t2.get('a') == 1
+
+        assert cnt1 == 0
+        assert t2.get('b') == 2
+        assert cnt1 == 1
+        assert t2.get('b') == 2
+        assert cnt1 == 1
+
+        assert (cnt1, cnt2) == (1, 0)
+        assert t2.get('c') == {'x': 2, 'y': 3}
+        assert (cnt1, cnt2) == (2, 1)
+        assert t2.get('c') == {'x': 2, 'y': 3}
+        assert (cnt1, cnt2) == (2, 1)
+
+        assert (cnt1, cnt2, cnt3) == (2, 1, 0)
+        assert t2.get('d').get('x') == 3
+        assert t2.get('d').get('y') == {'x': 3, 'y': 4}
+        assert (cnt1, cnt2, cnt3) == (2, 2, 1)
+        assert t2.get('d').get('x') == 3
+        assert t2.get('d').get('y') == {'x': 3, 'y': 4}
+        assert (cnt1, cnt2, cnt3) == (2, 2, 1)
+
     def test_get_or_default(self):
         t = create_storage({'a': 1, 'b': 2, 'c': raw({'x': 3, 'y': 4}), 'd': {'x': 3, 'y': 4}})
         assert t.get_or_default('a', 233) == 1
@@ -34,6 +80,23 @@ class TestTreeStorage:
 
         assert t.get_or_default('fff', 233) == 233
 
+        t1 = create_storage({
+            'a': delayed_partial(lambda: t.get('a')),
+            'b': delayed_partial(lambda: t.get('b')),
+            'c': delayed_partial(lambda: t.get('c')),
+            'd': delayed_partial(lambda: t.get('d')),
+        })
+        assert t1.get_or_default('a', 233) == 1
+        assert t1.get_or_default('b', 233) == 2
+        assert t1.get_or_default('c', 233) == {'x': 3, 'y': 4}
+        assert isinstance(t1.get_or_default('d', 233), TreeStorage)
+        assert t1.get_or_default('d', 233).get_or_default('x', 233) == 3
+        assert t1.get_or_default('d', 233).get_or_default('y', 233) == 4
+
+        assert t1.get_or_default('fff', 233) == 233
+        assert t1.get_or_default('fff', delayed_partial(lambda: 2345)) == 2345
+        assert not t1.contains('fff')
+
     def test_set(self):
         t = create_storage({})
         t.set('a', 1)
@@ -122,6 +185,19 @@ class TestTreeStorage:
         assert _dumped['d']['x'] == 3
         assert _dumped['d']['y'] == 4
 
+        t2 = create_storage({
+            'a': 1,
+            'b': delayed_partial(lambda x: x + 1, 1),
+            'c': delayed_partial(lambda: h1),
+            'd': delayed_partial(lambda: create_storage(h2)),
+        })
+        _dumped = t2.dump()
+        assert _dumped['a'] == 1
+        assert _dumped['b'] == 2
+        assert _dumped['c'].value() is h1
+        assert _dumped['d']['x'] == 3
+        assert _dumped['d']['y'] == 4
+
     def test_deepdump(self):
         h1 = {'x': 3, 'y': 4}
         h2 = {'x': 3, 'y': 4}
@@ -177,7 +253,7 @@ class TestTreeStorage:
         h2 = {'x': 3, 'y': 4}
         t = create_storage({'a': 1, 'b': 2, 'c': raw(h1), 'd': h2})
 
-        t1 = t.deepcopyx(lambda x: -x if isinstance(x, int) else {'holy': 'shit'})
+        t1 = t.deepcopyx(lambda x: -x if isinstance(x, int) else {'holy': 'shit'}, False)
         assert t1.get('a') == -1
         assert t1.get('b') == -2
         assert t1.get('c') == {'holy': 'shit'}
@@ -232,6 +308,19 @@ class TestTreeStorage:
         assert t1.get('f').get('y') == 4
         assert t1.get('f') is not t.get('f')
 
+        t2 = create_storage({
+            'a': delayed_partial(lambda: 11),
+            'b': delayed_partial(lambda: 22),
+            'c': delayed_partial(lambda: {'x': 3, 'y': 5}),
+            'd': delayed_partial(lambda: create_storage({'x': 3, 'y': 7})),
+        })
+        t1.copy_from(t2)
+        assert t1.get('a') == 11
+        assert t1.get('b') == 22
+        assert t1.get('c') == {'x': 3, 'y': 5}
+        assert t1.get('d').get('x') == 3
+        assert t1.get('d').get('y') == 7
+
     def test_deepcopy_from(self):
         h1 = {'x': 3, 'y': 4}
         h2 = {'x': 3, 'y': 4}
@@ -253,6 +342,19 @@ class TestTreeStorage:
         assert t1.get('f').get('y') == 4
         assert t1.get('f') is not t.get('f')
 
+        t2 = create_storage({
+            'a': delayed_partial(lambda: 11),
+            'b': delayed_partial(lambda: 22),
+            'c': delayed_partial(lambda: {'x': 3, 'y': 5}),
+            'd': delayed_partial(lambda: create_storage({'x': 3, 'y': 7})),
+        })
+        t1.deepcopy_from(t2)
+        assert t1.get('a') == 11
+        assert t1.get('b') == 22
+        assert t1.get('c') == {'x': 3, 'y': 5}
+        assert t1.get('d').get('x') == 3
+        assert t1.get('d').get('y') == 7
+
     def test_repr(self):
         h1 = {'x': 3, 'y': 4}
         h2 = {'x': 3, 'y': 4}
@@ -272,6 +374,21 @@ class TestTreeStorage:
         assert t == t
         assert t == t1
         assert t != t2
+        assert t != None
+
+        t3 = create_storage({
+            'a': delayed_partial(lambda: 11),
+            'b': delayed_partial(lambda: 22),
+            'c': delayed_partial(lambda: {'x': 3, 'y': 5}),
+            'd': delayed_partial(lambda: create_storage({'x': 3, 'y': 7})),
+        })
+        t4 = create_storage({
+            'a': delayed_partial(lambda: t3.get('a')),
+            'b': delayed_partial(lambda: t3.get('b')),
+            'c': delayed_partial(lambda: t3.get('c')),
+            'd': delayed_partial(lambda: t3.get('d')),
+        })
+        assert t3 == t4
 
     def test_keys(self):
         h1 = {'x': 3, 'y': 4}
@@ -286,10 +403,20 @@ class TestTreeStorage:
         t = create_storage({'a': 1, 'b': 2, 'd': h1})
 
         assert set(t.get('d').values()) == {3, 4}
-        assert len(t.values()) == 3
+        assert len(list(t.values())) == 3
         assert 1 in t.values()
         assert 2 in t.values()
 
+        t1 = create_storage({
+            'a': delayed_partial(lambda: t.get('a')),
+            'b': delayed_partial(lambda: t.get('b')),
+            'd': delayed_partial(lambda: t.get('d')),
+        })
+        assert set(t1.get('d').values()) == {3, 4}
+        assert len(list(t1.values())) == 3
+        assert 1 in t1.values()
+        assert 2 in t1.values()
+
     def test_items(self):
         h1 = {'x': 3, 'y': 4}
         t = create_storage({'a': 1, 'b': 2, 'd': raw(h1)})
@@ -303,3 +430,39 @@ class TestTreeStorage:
                 assert v == h1
             else:
                 pytest.fail('Should not reach here.')
+
+        t1 = create_storage({
+            'a': delayed_partial(lambda: t.get('a')),
+            'b': delayed_partial(lambda: t.get('b')),
+            'd': delayed_partial(lambda: t.get('d')),
+        })
+        for k, v in t1.items():
+            if k == 'a':
+                assert v == 1
+            elif k == 'b':
+                assert v == 2
+            elif k == 'd':
+                assert v == h1
+            else:
+                pytest.fail('Should not reach here.')
+
+    def test_hash(self):
+        h = {}
+
+        h1 = {'x': 3, 'y': 4}
+        t = create_storage({'a': 1, 'b': 2, 'd': h1})
+        t1 = create_storage({
+            'a': delayed_partial(lambda: t.get('a')),
+            'b': delayed_partial(lambda: t.get('b')),
+            'd': delayed_partial(lambda: t.get('d')),
+        })
+        t2 = create_storage({
+            'a': delayed_partial(lambda: t.get('a')),
+            'b': delayed_partial(lambda: 3),
+            'd': delayed_partial(lambda: t.get('d')),
+        })
+
+        h[t] = 1
+        assert t1 in h
+        assert h[t1] == 1
+        assert t2 not in h

test/tree/func/test_func.py

@@ -3,7 +3,7 @@ from operator import __mul__
 
 import pytest
 
-from treevalue.tree import func_treelize, TreeValue, method_treelize, classmethod_treelize
+from treevalue.tree import func_treelize, TreeValue, method_treelize, classmethod_treelize, delayed
 
 
 # noinspection DuplicatedCode
@@ -257,3 +257,147 @@ class TestTreeFuncFunc:
                 'f': [4],
             },
         })
+
+    def test_delay_support(self):
+        @func_treelize(return_type=TreeValue)
+        def f(x, y, z):
+            return x + y * 2 + z * 3
+
+        t1 = TreeValue({
+            'a': 1,
+            'b': delayed(lambda x: x ** 2, 3),
+            'c': {'x': 2, 'y': delayed(lambda: 4)},
+        })
+        t2 = TreeValue({
+            'a': delayed(lambda x: x + 1, t1.a),
+            'b': delayed(lambda: t1.c.y),
+            'c': delayed(lambda: 5),
+        })
+        t3 = delayed(lambda: 6)
+
+        assert f(t1, t2, t3) == TreeValue({
+            'a': 23, 'b': 35,
+            'c': {'x': 30, 'y': 32},
+        })
+
+        t1 = TreeValue({
+            'a': 1,
+            'b': delayed(lambda x: x ** 2, 3),
+            'c': {'x': 2, 'y': delayed(lambda: 4)},
+        })
+        t2 = TreeValue({
+            'a': delayed(lambda x: x + 1, t1.a),
+            'b': delayed(lambda: t1.c.y),
+            'c': delayed(lambda: 5),
+        })
+        t3 = delayed(lambda: 6)
+
+        assert f(x=t1, y=t2, z=t3) == TreeValue({
+            'a': 23, 'b': 35,
+            'c': {'x': 30, 'y': 32},
+        })
+
+    def test_delayed_treelize(self):
+        t1 = TreeValue({
+            'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4},
+        })
+        t2 = TreeValue({
+            'a': 11, 'b': 23, 'x': {'c': 35, 'd': 47},
+        })
+
+        cnt_1 = 0
+
+        @func_treelize(delayed=True)
+        def total(a, b):
+            nonlocal cnt_1
+            cnt_1 += 1
+            return a + b
+
+        # positional
+        t3 = total(t1, t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 38, 'd': 51})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 25, 'x': {'c': 38, 'd': 51}
+        })
+        assert cnt_1 == 4
+
+        # keyword
+        cnt_1 = 0
+        t3 = total(a=t1, b=t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 38, 'd': 51})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 25, 'x': {'c': 38, 'd': 51}
+        })
+        assert cnt_1 == 4
+
+        # positional, with constant
+        cnt_1 = 0
+        t3 = total(1, t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 36, 'd': 48})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 24, 'x': {'c': 36, 'd': 48}
+        })
+        assert cnt_1 == 4
+
+        # keyword, with constant
+        cnt_1 = 0
+        t3 = total(b=1, a=t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 36, 'd': 48})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 24, 'x': {'c': 36, 'd': 48}
+        })
+        assert cnt_1 == 4
+
+        # positional, with delay
+        cnt_1 = 0
+        t4 = TreeValue({'v': delayed(lambda: t1)})
+        t5 = TreeValue({'v': delayed(lambda: t2)})
+
+        t6 = total(t4, t5)
+        assert cnt_1 == 0
+
+        assert t6.v.a == 12
+        assert cnt_1 == 1
+        assert t6.v.x == TreeValue({'c': 38, 'd': 51})
+        assert cnt_1 == 3
+        assert t6 == TreeValue({
+            'v': {'a': 12, 'b': 25, 'x': {'c': 38, 'd': 51}},
+        })
+        assert cnt_1 == 4
+
+        # keyword, with delay
+        cnt_1 = 0
+        t4 = TreeValue({'v': delayed(lambda: t1)})
+        t5 = TreeValue({'v': delayed(lambda: t2)})
+
+        t6 = total(a=t4, b=t5)
+        assert cnt_1 == 0
+
+        assert t6.v.a == 12
+        assert cnt_1 == 1
+        assert t6.v.x == TreeValue({'c': 38, 'd': 51})
+        assert cnt_1 == 3
+        assert t6 == TreeValue({
+            'v': {'a': 12, 'b': 25, 'x': {'c': 38, 'd': 51}},
+        })
+        assert cnt_1 == 4

test/tree/func/test_outer.py

@@ -38,3 +38,46 @@ class TestTreeFuncOuter:
 
         with pytest.raises(KeyError):
             _ = ssum(t1, t3)
+
+    def test_delayed_treelize(self):
+        t1 = TreeValue({
+            'a': 1, 'x': {'c': 3, 'd': 4},
+        })
+        t2 = TreeValue({
+            'a': 11, 'b': 23, 'x': {'c': 35, },
+        })
+
+        cnt_1 = 0
+
+        @func_treelize(delayed=True, mode='outer', missing=0)
+        def total(a, b):
+            nonlocal cnt_1
+            cnt_1 += 1
+            return a + b
+
+        # positional
+        t3 = total(t1, t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 38, 'd': 4})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 23, 'x': {'c': 38, 'd': 4}
+        })
+        assert cnt_1 == 4
+
+        # keyword
+        cnt_1 = 0
+        t3 = total(a=t1, b=t2)
+        assert cnt_1 == 0
+
+        assert t3.a == 12
+        assert cnt_1 == 1
+        assert t3.x == TreeValue({'c': 38, 'd': 4})
+        assert cnt_1 == 3
+        assert t3 == TreeValue({
+            'a': 12, 'b': 23, 'x': {'c': 38, 'd': 4}
+        })
+        assert cnt_1 == 4

test/tree/general/base.py

@@ -5,7 +5,7 @@ from typing import Type
 import numpy as np
 import pytest
 
-from treevalue.tree import func_treelize, TreeValue, raw, mapping
+from treevalue.tree import func_treelize, TreeValue, raw, mapping, delayed
 
 
 def get_tree_test(tree_value_clazz: Type[TreeValue]):
@@ -356,8 +356,38 @@ def get_tree_test(tree_value_clazz: Type[TreeValue]):
             assert t2.add(t1) == tree_value_clazz({'a': 2, 'b': 4, 'x': {'c': 6, 'd': 8}})
 
         def test_map(self):
+            cnt = 0
+
+            def f(x):
+                nonlocal cnt
+                cnt += 1
+                return x + 2
+
             t1 = tree_value_clazz({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
-            assert t1.map(lambda x: x + 2) == tree_value_clazz({'a': 3, 'b': 4, 'x': {'c': 5, 'd': 6}})
+            assert cnt == 0
+            t2 = t1.map(f)
+            assert cnt == 4
+            assert t2 == tree_value_clazz({'a': 3, 'b': 4, 'x': {'c': 5, 'd': 6}})
+
+            cnt = 0
+            t3 = tree_value_clazz({
+                'a': delayed(lambda: t1.a),
+                'b': delayed(lambda: t1.b),
+                'x': delayed(lambda: t1.x),
+            })
+            assert cnt == 0
+
+            t4 = t3.map(f, delayed=True)
+            assert cnt == 0
+
+            assert t4.a == 3
+            assert cnt == 1
+
+            assert t4 == tree_value_clazz({'a': 3, 'b': 4, 'x': {'c': 5, 'd': 6}})
+            assert cnt == 4
+
+            assert t4.a == 3
+            assert cnt == 4
 
         def test_type(self):
             t1 = tree_value_clazz({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
@@ -572,4 +602,23 @@ def get_tree_test(tree_value_clazz: Type[TreeValue]):
 
             assert ssum(t1, t2) == tree_value_clazz({'a': 12, 'b': 22, 'x': {'c': 36, 'd': 52}})
 
+            cnt_1 = 0
+
+            @tree_value_clazz.func(delayed=True)
+            def ssumx(x, y):
+                nonlocal cnt_1
+                cnt_1 += 1
+                return x + y
+
+            cnt_1 = 0
+            t3 = ssumx(t1, t2)
+            assert cnt_1 == 0
+
+            assert t3.a == 12
+            assert cnt_1 == 1
+            assert t3.x == tree_value_clazz({'c': 36, 'd': 52})
+            assert cnt_1 == 3
+            assert t3 == tree_value_clazz({'a': 12, 'b': 22, 'x': {'c': 36, 'd': 52}})
+            assert cnt_1 == 4
+
     return _TestClass

test/tree/tree/test_flatten.py

 import pytest
 
-from treevalue.tree import TreeValue, raw, flatten, unflatten, flatten_values, flatten_keys
+from treevalue.tree import TreeValue, raw, flatten, unflatten, flatten_values, flatten_keys, delayed
 
 
 class MyTreeValue(TreeValue):
@@ -22,15 +22,37 @@ class TestTreeTreeFlatten:
             (('d', 'y'), 4)
         ]
 
+        t1 = TreeValue({
+            'a': delayed(lambda: t.a),
+            'b': delayed(lambda: t.b),
+            'c': delayed(lambda: t.c),
+            'd': delayed(lambda: t.d),
+        })
+        flatted = sorted(flatten(t1))
+        assert flatted == [
+            (('a',), 1),
+            (('b',), 2),
+            (('c',), {'x': 3, 'y': 4}),
+            (('d', 'x'), 3),
+            (('d', 'y'), 4)
+        ]
+
     def test_flatten_values(self):
         t = TreeValue({'a': 1, 'b': 5, 'c': {'x': 3, 'y': 4}, 'd': {'x': 3, 'y': 4}})
-
         flatted_values = sorted(flatten_values(t))
         assert flatted_values == [1, 3, 3, 4, 4, 5]
 
+        t1 = TreeValue({
+            'a': delayed(lambda: t.a),
+            'b': delayed(lambda: t.b),
+            'c': delayed(lambda: t.c),
+            'd': delayed(lambda: t.d),
+        })
+        flatted_values = sorted(flatten_values(t1))
+        assert flatted_values == [1, 3, 3, 4, 4, 5]
+
     def test_flatten_keys(self):
         t = TreeValue({'a': 1, 'd': {'x': 3, 'y': 4}, 'e': raw({'x': 3, 'y': 4}), 'b': 5, 'c': {'x': 3, 'y': 4}})
-
         flatted_keys = sorted(flatten_keys(t))
         assert flatted_keys == [
             ('a',),
@@ -42,6 +64,24 @@ class TestTreeTreeFlatten:
             ('e',),
         ]
 
+        t1 = TreeValue({
+            'a': delayed(lambda: t.a),
+            'b': delayed(lambda: t.b),
+            'c': delayed(lambda: t.c),
+            'd': delayed(lambda: t.d),
+            'e': delayed(lambda: t.e),
+        })
+        flatted_keys = sorted(flatten_keys(t1))
+        assert flatted_keys == [
+            ('a',),
+            ('b',),
+            ('c', 'x',),
+            ('c', 'y',),
+            ('d', 'x',),
+            ('d', 'y',),
+            ('e',),
+        ]
+
     def test_unflatten(self):
         flatted = [
             (('a',), 1),

test/tree/tree/test_functional.py

@@ -3,7 +3,7 @@ from operator import __mul__
 
 import pytest
 
-from treevalue.tree import TreeValue, mapping, raw, mask, filter_, reduce_
+from treevalue.tree import TreeValue, mapping, raw, mask, filter_, reduce_, delayed
 
 
 # noinspection DuplicatedCode
@@ -30,6 +30,59 @@ class TestTreeTreeFunctional:
         })
         assert tv6 == TreeValue({'a': 1.0, 'b': 2.0, 'c': {'x': 2.0, 'y': 3.0}})
 
+        tv8 = TreeValue({'v': delayed(lambda: tv1)})
+        assert mapping(tv8, lambda x: x + 2) == TreeValue({'v': {
+            'a': 3, 'b': 4, 'c': {'x': 4, 'y': 5}
+        }})
+
+    def test_mapping_delayed(self):
+        tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})
+        tv8 = TreeValue({'v': delayed(lambda: tv1)})
+        assert mapping(tv8, lambda x: x + 2, delayed=True) == TreeValue({'v': {
+            'a': 3, 'b': 4, 'c': {'x': 4, 'y': 5}
+        }})
+
+        cnt_f, cnt_v = 0, 0
+
+        def f(x):
+            nonlocal cnt_f
+            cnt_f += 1
+            return TreeValue({
+                'a': x * 2, 'b': x + 1, 'c': x ** 2,
+            })
+
+        def v():
+            nonlocal cnt_v
+            cnt_v += 1
+            return 3
+
+        t = TreeValue({
+            'a': 1, 'b': delayed(f, 1),
+            'x': {'c': delayed(v), 'd': 4, },
+            'y': delayed(f, 3),
+        })
+        t1 = mapping(t, lambda x: (x + 3) ** 2, delayed=True)
+        assert cnt_v == 0
+        assert cnt_f == 0
+
+        assert t1 == TreeValue({
+            'a': 16,
+            'b': {'a': 25, 'b': 25, 'c': 16, },
+            'x': {'c': 36, 'd': 49, },
+            'y': {'a': 81, 'b': 49, 'c': 144, },
+        })
+        assert cnt_v == 1
+        assert cnt_f == 2
+
+        assert t == TreeValue({
+            'a': 1,
+            'b': {'a': 2, 'b': 2, 'c': 1, },
+            'x': {'c': 3, 'd': 4, },
+            'y': {'a': 6, 'b': 4, 'c': 9, },
+        })
+        assert cnt_v == 1
+        assert cnt_f == 2
+
     def test_mask(self):
         class MyTreeValue(TreeValue):
             pass
@@ -46,6 +99,10 @@ class TestTreeTreeFunctional:
         with pytest.raises(TypeError):
             assert mask(t2, m2)
 
+        t1 = TreeValue({'v': delayed(lambda: t)})
+        m11 = TreeValue({'v': delayed(lambda: m1)})
+        assert mask(t1, m11) == TreeValue({'v': {'a': 1}})
+
     def test_filter(self):
         class MyTreeValue(TreeValue):
             pass
@@ -56,6 +113,9 @@ class TestTreeTreeFunctional:
         assert filter_(t, lambda x: x < 3, remove_empty=False) == MyTreeValue({'a': 1, 'b': 2, 'x': {}})
         assert filter_(t, lambda x: x % 2 == 1) == MyTreeValue({'a': 1, 'x': {'c': 3}})
 
+        t2 = TreeValue({'v': delayed(lambda: t)})
+        assert filter_(t2, lambda x: x < 3) == TreeValue({'v': {'a': 1, 'b': 2}})
+
     def test_reduce(self):
         class MyTreeValue(TreeValue):
             pass
@@ -74,3 +134,8 @@ class TestTreeTreeFunctional:
         assert reduce_(t2, lambda **kwargs: TreeValue(
             {k + k: (v ** 2 if not isinstance(v, TreeValue) else v) for k, v in kwargs.items()})) == MyTreeValue(
             {'aa': 1, 'bb': 4, 'xx': {'cc': 9, 'dd': 16}})
+
+        t1 = MyTreeValue({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
+        t3 = TreeValue({'v': delayed(lambda: t1), 'v2': delayed(lambda: t1)})
+        assert reduce_(t3, lambda **kwargs: sum(kwargs.values())) == 20
+        assert reduce_(t3, lambda **kwargs: reduce(__mul__, list(kwargs.values()))) == 576

test/tree/tree/test_service.py

 import pytest
 
-from treevalue.tree import jsonify, TreeValue, clone, typetrans, raw, walk
+from treevalue.tree import jsonify, TreeValue, clone, typetrans, raw, walk, delayed
 
 
 # noinspection DuplicatedCode
@@ -19,6 +19,18 @@ class TestTreeTreeService:
         }
         assert tv2.c == {'x': 2, 'y': 3}
 
+        tv3 = TreeValue({
+            'a': delayed(lambda: tv1.a),
+            'b': delayed(lambda: tv1.b),
+            'c1': delayed(lambda: tv1.c),
+            'c2': delayed(lambda: tv2.c),
+        })
+        assert jsonify(tv3) == {
+            'a': 1, 'b': 2, 'c1': {'x': 2, 'y': 3}, 'c2': {'x': 2, 'y': 3}
+        }
+        assert tv3.c1 == TreeValue({'x': 2, 'y': 3})
+        assert tv3.c2 == {'x': 2, 'y': 3}
+
     def test_clone(self):
         tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})
         tv2 = clone(tv1)
@@ -63,6 +75,14 @@ class TestTreeTreeService:
         assert tv5.x.c is not tv3.x.c
         assert tv5.x.d is not tv3.x.d
 
+        tv6 = TreeValue({
+            'a': delayed(lambda: tv3.a),
+            'b': delayed(lambda: tv3.b),
+            'x': delayed(lambda: tv3.x),
+        })
+        tv7 = clone(tv6, lambda x: x)
+        assert tv7 == tv3
+
     def test_typetrans(self):
         class MyTreeValue(TreeValue):
             pass
@@ -99,3 +119,15 @@ class TestTreeTreeService:
             ('c', 'x',): 2,
             ('c', 'y',): 3,
         }
+
+        tv2 = MyTreeValue({
+            'a': delayed(lambda: tv1.a),
+            'b': delayed(lambda: tv1.b),
+            'c': delayed(lambda: tv1.c),
+        })
+        assert dict(walk(tv2)) == {
+            ('a',): 1,
+            ('b',): 2,
+            ('c', 'x',): 2,
+            ('c', 'y',): 3,
+        }

test/tree/tree/test_structural.py

 import pytest
 
-from treevalue.tree import TreeValue, mapping, union, raw, subside, rise
+from treevalue.tree import TreeValue, mapping, union, raw, subside, rise, delayed
 
 
 # noinspection DuplicatedCode
@@ -16,10 +16,37 @@ class TestTreeTreeStructural:
 
         t1 = MyTreeValue({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
         assert union(t, t1) == TreeValue({'a': (1, 1), 'b': (2, 2), 'x': {'c': (3, 3), 'd': (4, 4)}})
+        assert union(t, t1, return_type=MyTreeValue) == MyTreeValue(
+            {'a': (1, 1), 'b': (2, 2), 'x': {'c': (3, 3), 'd': (4, 4)}})
         assert union(t1, t) == MyTreeValue({'a': (1, 1), 'b': (2, 2), 'x': {'c': (3, 3), 'd': (4, 4)}})
         assert union(1, 2) == (1, 2)
         assert union(1, 2, return_type=TreeValue) == (1, 2)
 
+        tp = MyTreeValue({'v': delayed(lambda: t)})
+        tp1 = TreeValue({'v': delayed(lambda: t1)})
+        assert union(tp, tp1) == MyTreeValue({'v': {'a': (1, 1), 'b': (2, 2), 'x': {'c': (3, 3), 'd': (4, 4)}}})
+        assert union(tp1, tp) == TreeValue({'v': {'a': (1, 1), 'b': (2, 2), 'x': {'c': (3, 3), 'd': (4, 4)}}})
+
+        t = MyTreeValue({'a': 1, 'b': 2, 'x': {'c': 3}})
+        t1 = TreeValue({
+            'a': delayed(lambda: t.x.c),
+            'x': {
+                'c': delayed(lambda: t.a),
+                'd': delayed(lambda: t.b),
+            }
+        })
+        assert union(t, t1, mode='outer', missing=None) == MyTreeValue({
+            'a': (1, 3), 'b': (2, None), 'x': {'c': (3, 1), 'd': (None, 2)},
+        })
+
+    def test_union_delayed(self):
+        class MyTreeValue(TreeValue):
+            pass
+
+        t = TreeValue({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
+        t1 = MyTreeValue({'a': 11, 'b': 22, 'x': {'c': 33, 'd': 44}})
+        assert union(t, t1, delayed=True) == TreeValue({'a': (1, 11), 'b': (2, 22), 'x': {'c': (3, 33), 'd': (4, 44)}})
+
     def test_subside(self):
         assert subside({'a': (1, 2), 'b': [3, 4]}) == {'a': (1, 2), 'b': [3, 4]}
         assert subside({'a': (1, 2), 'b': [3, 4]}, return_type=TreeValue) == {'a': (1, 2), 'b': [3, 4]}
@@ -88,6 +115,30 @@ class TestTreeTreeStructural:
         assert subside({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}, 'e': [3, 4, 5]}) == \
                {'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}, 'e': [3, 4, 5]}
 
+    def test_subside_delayed(self):
+        class MyTreeValue(TreeValue):
+            pass
+
+        original2 = {
+            'a': TreeValue({'a': 1, 'b': 2}),
+            'x': {
+                'c': MyTreeValue({'a': 3, 'b': 4}),
+                'd': [
+                    MyTreeValue({'a': 5, 'b': 6}),
+                    MyTreeValue({'a': 7, 'b': 8}),
+                ]
+            },
+            'k': '233'
+        }
+        assert subside(original2, delayed=True) == TreeValue({
+            'a': raw({'a': 1, 'k': '233', 'x': {'c': 3, 'd': [5, 7]}}),
+            'b': raw({'a': 2, 'k': '233', 'x': {'c': 4, 'd': [6, 8]}}),
+        })
+        assert subside(original2, return_type=MyTreeValue, delayed=True) == MyTreeValue({
+            'a': raw({'a': 1, 'k': '233', 'x': {'c': 3, 'd': [5, 7]}}),
+            'b': raw({'a': 2, 'k': '233', 'x': {'c': 4, 'd': [6, 8]}}),
+        })
+
     def test_rise(self):
         t1 = TreeValue({'x': raw({'a': [1, 2], 'b': [2, 3]}), 'y': raw({'a': [5, 6, 7], 'b': [7, 8]})})
         assert rise(t1) == {
@@ -203,3 +254,21 @@ class TestTreeTreeStructural:
             rise(t5, template=[object, object, object, object, object, ...])
 
         assert rise(1) == 1
+
+        t1 = TreeValue({'x': raw({'a': [1, 2], 'b': [2, 3]}), 'y': raw({'a': [5, 6, 7], 'b': [7, 8]})})
+        assert rise(t1) == {
+            'a': TreeValue({'x': [1, 2], 'y': [5, 6, 7]}),
+            'b': [
+                TreeValue({'x': 2, 'y': 7}),
+                TreeValue({'x': 3, 'y': 8}),
+            ]
+        }
+
+        t10 = MyTreeValue({'v': delayed(lambda: t1)})
+        assert rise(t10) == {
+            'a': MyTreeValue({'v': {'x': [1, 2], 'y': [5, 6, 7]}}),
+            'b': [
+                MyTreeValue({'v': {'x': 2, 'y': 7}}),
+                MyTreeValue({'v': {'x': 3, 'y': 8}}),
+            ]
+        }

test/tree/tree/test_tree.py

@@ -3,7 +3,7 @@ import re
 
 import pytest
 
-from treevalue import raw, TreeValue
+from treevalue import raw, TreeValue, delayed
 
 
 class _Container:
@@ -121,6 +121,20 @@ class TestTreeTreeTree:
         assert "c --> <TreeValue" in repr(tv2)
         assert "(The same address as <root>)" in repr(tv2)
 
+        tv3 = TreeValue({
+            'a': delayed(lambda: tv1.a),
+            'b': delayed(lambda: tv1.b),
+            'c': delayed(lambda: tv1.c),
+        })
+
+        assert re.match(r"<TreeValue 0x[0-9a-f]+>", repr(tv3))
+        assert re.match(r"<TreeValue 0x[0-9a-f]+>", repr(tv3.c))
+        assert "a --> 1" in str(tv3)
+        assert "b --> 2" in str(tv3)
+        assert "x --> 2" in str(tv3)
+        assert "y --> 3" in str(tv3)
+        assert "c --> <TreeValue" in str(tv3)
+
     def test_tree_value_iter(self):
         # Attention: dict(tv1) is not supported in python 3.7+
         tv1 = TreeValue({'a': 1, 'b': 2, 'c': {'x': 2, 'y': 3}})

treevalue/tree/common/__init__.py

 from .base import raw, unraw, RawWrapper
+from .delay import DelayedProxy, delayed_partial, undelay, DelayedValueProxy, DelayedFuncProxy
 from .storage import TreeStorage, create_storage

treevalue/tree/common/base.pyx

@@ -39,7 +39,7 @@ cdef class RawWrapper:
         self.val = state
 
 @cython.binding(True)
-cpdef public object raw(object obj):
+cpdef inline object raw(object obj):
     """
     Overview:
         Try wrap the given ``obj`` to raw wrapper.
@@ -57,7 +57,7 @@ cpdef public object raw(object obj):
         return obj
 
 @cython.binding(True)
-cpdef public object unraw(object wrapped):
+cpdef inline object unraw(object wrapped):
     """
     Overview:
         Try unwrap the given ``wrapped`` to original object.

treevalue/tree/common/delay.pxd

+# distutils:language=c++
+# cython:language_level=3
+
+from libcpp cimport bool
+
+cdef class DelayedProxy:
+    cpdef object value(self)
+    cpdef object fvalue(self)
+
+cdef class DelayedValueProxy(DelayedProxy):
+    cdef readonly object func
+    cdef readonly bool calculated
+    cdef object val
+
+    cpdef object value(self)
+
+cdef class DelayedFuncProxy(DelayedProxy):
+    cdef readonly object func
+    cdef readonly tuple args
+    cdef readonly dict kwargs
+    cdef readonly bool calculated
+    cdef object val
+
+    cpdef object value(self)
+
+cdef DelayedProxy _c_delayed_partial(func, args, kwargs)
+cpdef object undelay(object p, bool is_final= *)

treevalue/tree/common/delay.pyx

+# distutils:language=c++
+# cython:language_level=3
+
+import cython
+from libcpp cimport bool
+
+cdef class DelayedProxy:
+    """
+    Overview:
+        Base class of all the delayed proxy class.
+    """
+    cpdef object value(self):
+        r"""
+        Overview:
+            Get value of the delayed proxy.
+            Should make sure the result is cached.
+            Can be accessed in :func:`treevalue.tree.common.undelay` when ``is_final`` is ``False``.
+
+        Returns:
+            - value (:obj:`object`): Calculation result.
+        """
+        raise NotImplementedError  # pragma: no cover
+
+    cpdef object fvalue(self):
+        r"""
+        Overview:
+            Get value of the delayed proxy.
+            Can be accessed in :func:`treevalue.tree.common.undelay` when ``is_final`` is ``True``.
+
+        Returns:
+            - value (:obj:`object`): Calculation result.
+        """
+        return self.value()
+
+cdef class DelayedValueProxy(DelayedProxy):
+    """
+    Overview:
+        Simple function delayed proxy.
+    """
+    def __cinit__(self, object func):
+        """
+        Overview:
+            Constructor of class :class:`treevalue.tree.common.DelayedValueProxy`.
+
+        Arguments:
+            - func (:obj:`object`): Function to be called, which can be called without arguments. \
+                Delayed proxy is supported.
+        """
+        self.func = func
+        self.calculated = False
+        self.val = None
+
+    cpdef object value(self):
+        cdef object f
+        if not self.calculated:
+            f = undelay(self.func, False)
+            self.val = f()
+            self.calculated = True
+
+        return self.val
+
+cdef class DelayedFuncProxy(DelayedProxy):
+    """
+    Overview:
+        Simple function delayed proxy.
+    """
+    def __cinit__(self, object func, tuple args, dict kwargs):
+        """
+        Overview:
+            Constructor of class :class:`treevalue.tree.common.DelayedFuncProxy`.
+
+        Arguments:
+            - func (:obj:`object`): Function to be called, which can be called with given arguments. \
+                Delayed proxy is supported.
+            - args (:obj:`tuple`): Positional arguments to be used, delayed proxy is supported.
+            - kwargs (:obj:`dict`): Key-word arguments to be used, delayed proxy is supported.
+        """
+        self.func = func
+        self.args = args
+        self.kwargs = kwargs
+        self.calculated = False
+        self.val = None
+
+    cpdef object value(self):
+        cdef list pas
+        cdef dict pks
+        cdef str key
+        cdef object item
+        cdef object f
+        if not self.calculated:
+            pas = []
+            pks = {}
+            f = undelay(self.func, False)
+            for item in self.args:
+                pas.append(undelay(item, False))
+            for key, item in self.kwargs.items():
+                pks[key] = undelay(item, False)
+
+            self.val = f(*pas, **pks)
+            self.calculated = True
+
+        return self.val
+
+cdef inline DelayedProxy _c_delayed_partial(func, args, kwargs):
+    if args or kwargs:
+        return DelayedFuncProxy(func, args, kwargs)
+    else:
+        return DelayedValueProxy(func)
+
+@cython.binding(True)
+def delayed_partial(func, *args, **kwargs):
+    """
+    Overview:
+        Build a delayed partial object.
+        Similar to :func:`functools.partial`.
+
+    Returns:
+        - delayed: Delayed object.
+    """
+    return _c_delayed_partial(func, args, kwargs)
+
+@cython.binding(True)
+cpdef inline object undelay(object p, bool is_final=True):
+    r"""
+    Overview:
+        Get the value of a given object, it can be a delayed proxy, a simple object or \
+            a nested delayed proxy.
+    
+    Arguments:
+        - p (:obj:`object`): Given object to be undelay.
+        - is_final (:obj:`bool`): Is final value getting or not, default is ``True``. 
+
+    Returns:
+        - value (:obj:`object): Actual value of the given ``p``.
+    """
+    if isinstance(p, DelayedProxy):
+        if is_final:
+            return p.fvalue()
+        else:
+            return p.value()
+    else:
+        return p

treevalue/tree/common/storage.pxd

 # distutils:language=c++
 # cython:language_level=3
 
+from libcpp cimport bool
+
 ctypedef unsigned char boolean
 ctypedef unsigned int uint
 
-cdef void _key_validate(const char*key) except *
+cdef void _key_validate(const char *key) except *
 
 cdef class TreeStorage:
     cdef readonly dict map
@@ -19,13 +21,16 @@ cdef class TreeStorage:
     cpdef public dict dump(self)
     cpdef public dict deepdump(self)
     cpdef public dict deepdumpx(self, copy_func)
-    cpdef public dict jsondumpx(self, copy_func, object need_raw)
+    cpdef public dict jsondumpx(self, copy_func, bool need_raw, bool allow_delayed)
     cpdef public TreeStorage copy(self)
     cpdef public TreeStorage deepcopy(self)
-    cpdef public TreeStorage deepcopyx(self, copy_func)
+    cpdef public TreeStorage deepcopyx(self, copy_func, bool allow_delayed)
     cpdef public dict detach(self)
     cpdef public void copy_from(self, TreeStorage ts)
     cpdef public void deepcopy_from(self, TreeStorage ts)
-    cpdef public void deepcopyx_from(self, TreeStorage ts, copy_func)
+    cpdef public void deepcopyx_from(self, TreeStorage ts, copy_func, bool allow_delayed)
 
 cpdef public object create_storage(dict value)
+cdef object _c_undelay_data(dict data, object k, object v)
+cdef object _c_undelay_not_none_data(dict data, object k, object v)
+cdef object _c_undelay_check_data(dict data, object k, object v)

treevalue/tree/common/storage.pyx

@@ -4,13 +4,15 @@
 from copy import deepcopy
 
 from libc.string cimport strlen
+from libcpp cimport bool
 
 from .base cimport raw, unraw
+from .delay cimport undelay
 
 cdef inline object _keep_object(object obj):
     return obj
 
-cdef inline void _key_validate(const char*key) except *:
+cdef inline void _key_validate(const char *key) except *:
     cdef int n = strlen(key)
     if n < 1:
         raise KeyError(f'Key {repr(key)} is too short, minimum length is 1 but {n} found.')
@@ -35,13 +37,17 @@ cdef class TreeStorage:
         self.map[key] = value
 
     cpdef public object get(self, str key):
+        cdef object v, nv
         try:
-            return self.map[key]
+            v = self.map[key]
+            return _c_undelay_data(self.map, key, v)
         except KeyError:
             raise KeyError(f"Key {repr(key)} not found in this tree.")
 
     cpdef public object get_or_default(self, str key, object default):
-        return self.map.get(key, default)
+        cdef object v, nv
+        v = self.map.get(key, default)
+        return _c_undelay_check_data(self.map, key, v)
 
     cpdef public void del_(self, str key) except *:
         try:
@@ -65,17 +71,20 @@ cdef class TreeStorage:
         return self.deepdumpx(deepcopy)
 
     cpdef public dict deepdumpx(self, copy_func):
-        return self.jsondumpx(copy_func, True)
+        return self.jsondumpx(copy_func, True, False)
 
-    cpdef public dict jsondumpx(self, copy_func, object need_raw):
+    cpdef public dict jsondumpx(self, copy_func, bool need_raw, bool allow_delayed):
         cdef dict result = {}
         cdef str k
-        cdef object v, obj
+        cdef object v, obj, nv
         for k, v in self.map.items():
+            if not allow_delayed:
+                v = _c_undelay_data(self.map, k, v)
+
             if isinstance(v, TreeStorage):
-                result[k] = v.jsondumpx(copy_func, need_raw)
+                result[k] = v.jsondumpx(copy_func, need_raw, allow_delayed)
             else:
-                obj = copy_func(v)
+                obj = copy_func(v) if not allow_delayed else v
                 if need_raw:
                     obj = raw(obj)
                 result[k] = obj
@@ -83,43 +92,48 @@ cdef class TreeStorage:
         return result
 
     cpdef public TreeStorage copy(self):
-        return self.deepcopyx(_keep_object)
+        return self.deepcopyx(_keep_object, True)
 
     cpdef public TreeStorage deepcopy(self):
-        return self.deepcopyx(deepcopy)
+        return self.deepcopyx(deepcopy, False)
 
-    cpdef public TreeStorage deepcopyx(self, copy_func):
-        cdef type cls = type(self)
-        return create_storage(self.deepdumpx(copy_func))
+    cpdef public TreeStorage deepcopyx(self, copy_func, bool allow_delayed):
+        return create_storage(self.jsondumpx(copy_func, True, allow_delayed))
 
     cpdef public dict detach(self):
         return self.map
 
     cpdef public void copy_from(self, TreeStorage ts):
-        self.deepcopyx_from(ts, _keep_object)
+        self.deepcopyx_from(ts, _keep_object, True)
 
     cpdef public void deepcopy_from(self, TreeStorage ts):
-        self.deepcopyx_from(ts, deepcopy)
+        self.deepcopyx_from(ts, deepcopy, False)
 
-    cpdef public void deepcopyx_from(self, TreeStorage ts, copy_func):
+    cpdef public void deepcopyx_from(self, TreeStorage ts, copy_func, bool allow_delayed):
         cdef dict detached = ts.detach()
         cdef set keys = set(self.map.keys()) | set(detached.keys())
 
         cdef str k
-        cdef object
+        cdef object v, nv
         cdef TreeStorage newv
         for k in keys:
             if k in detached:
                 v = detached[k]
+                if not allow_delayed:
+                    v = _c_undelay_data(detached, k, v)
+
                 if isinstance(v, TreeStorage):
                     if k in self.map and isinstance(self.map[k], TreeStorage):
-                        self.map[k].copy_from(v)
+                        self.map[k].deepcopyx_from(v, copy_func, allow_delayed)
                     else:
                         newv = TreeStorage({})
-                        newv.copy_from(v)
+                        newv.deepcopyx_from(v, copy_func, allow_delayed)
                         self.map[k] = newv
                 else:
+                    if not allow_delayed:
                         self.map[k] = copy_func(v)
+                    else:
+                        self.map[k] = v
             else:
                 del self.map[k]
 
@@ -145,12 +159,16 @@ cdef class TreeStorage:
         cdef list other_keys = sorted(other.detach().keys())
 
         cdef str key
-        cdef object self_v
-        cdef object other_v
+        cdef object self_v, self_nv
+        cdef object other_v, other_nv
         if self_keys == other_keys:
             for key in self_keys:
                 self_v = self.map[key]
+                self_v = _c_undelay_data(self.map, key, self_v)
+
                 other_v = other_map[key]
+                other_v = _c_undelay_data(other_map, key, other_v)
+
                 if self_v != other_v:
                     return False
             return True
@@ -161,7 +179,7 @@ cdef class TreeStorage:
         cdef str k
         cdef object v
         cdef list _items = []
-        for k, v in sorted(self.map.items(), key=lambda x: x[0]):
+        for k, v in sorted(self.items(), key=lambda x: x[0]):
             _items.append((k, v))
 
         return hash(tuple(_items))
@@ -170,10 +188,18 @@ cdef class TreeStorage:
         return self.map.keys()
 
     def values(self):
-        return self.map.values()
+        cdef str k
+        cdef object v, nv
+        for k, v in self.map.items():
+            yield _c_undelay_data(self.map, k, v)
 
     def items(self):
-        return self.map.items()
+        cdef str k
+        cdef object v, nv
+        for k, v in self.map.items():
+            v = _c_undelay_data(self.map, k, v)
+
+            yield k, v
 
 cpdef object create_storage(dict value):
     cdef dict _map = {}
@@ -187,3 +213,21 @@ cpdef object create_storage(dict value):
             _map[k] = unraw(v)
 
     return TreeStorage(_map)
+
+cdef inline object _c_undelay_data(dict data, object k, object v):
+    cdef object nv = undelay(v)
+    if nv is not v:
+        data[k] = nv
+    return nv
+
+cdef inline object _c_undelay_not_none_data(dict data, object k, object v):
+    cdef object nv = undelay(v)
+    if nv is not v and k is not None:
+        data[k] = nv
+    return nv
+
+cdef inline object _c_undelay_check_data(dict data, object k, object v):
+    cdef object nv = undelay(v)
+    if nv is not v and k in data:
+        data[k] = nv
+    return nv
\ No newline at end of file

treevalue/tree/func/cfunc.pxd

@@ -5,11 +5,14 @@ from libcpp cimport bool
 
 from .modes cimport _e_tree_mode
 
-cdef object _c_func_treelize_run(object func, list args, dict kwargs,
-                                 _e_tree_mode mode, bool inherit, bool allow_missing, object missing_func)
+cdef object _c_wrap_func_treelize_run(object func, list args, dict kwargs, _e_tree_mode mode, bool inherit,
+                                      bool allow_missing, object missing_func, bool delayed)
+cdef object _c_func_treelize_run(object func, list args, dict kwargs, _e_tree_mode mode, bool inherit,
+                                 bool allow_missing, object missing_func, bool delayed)
 
 cpdef object _d_func_treelize(object func, object mode, object return_type, bool inherit, object missing,
-                              object subside, object rise)
-cdef _c_common_value(object item)
+                              bool delayed, object subside, object rise)
+cdef object _c_common_value(object item)
+cdef tuple _c_missing_process(object missing)
 cpdef object func_treelize(object mode= *, object return_type= *, bool inherit= *, object missing= *,
-                           object subside= *, object rise= *)
+                           bool delayed= *, object subside= *, object rise= *)

treevalue/tree/func/cfunc.pyx

@@ -8,20 +8,40 @@ from hbutils.design import SingletonMark
 from libcpp cimport bool
 
 from .modes cimport _e_tree_mode, _c_keyset, _c_load_mode, _c_check
-from ..common.storage cimport TreeStorage
+from ..common.delay import delayed_partial
+from ..common.delay cimport undelay
+from ..common.storage cimport TreeStorage, _c_undelay_not_none_data, _c_undelay_data
 from ..tree.structural cimport _c_subside, _c_rise
 from ..tree.tree cimport TreeValue
 
 _VALUE_IS_MISSING = SingletonMark('value_is_missing')
+MISSING_NOT_ALLOW = SingletonMark("missing_not_allow")
+
+
+
+cdef inline object _c_wrap_func_treelize_run(object func, list args, dict kwargs, _e_tree_mode mode, bool inherit,
+                                             bool allow_missing, object missing_func, bool delayed):
+    cdef list _l_args = []
+    cdef dict _d_kwargs = {}
+    cdef str k, ak
+    cdef object av, v, nv
+    for av, k, v in args:
+        _l_args.append(_c_undelay_not_none_data(av, k, v))
 
-cdef object _c_func_treelize_run(object func, list args, dict kwargs,
-                                 _e_tree_mode mode, bool inherit, bool allow_missing, object missing_func):
+    for ak, (av, k, v) in kwargs.items():
+        _d_kwargs[ak] = _c_undelay_not_none_data(av, k, v)
+
+    return _c_func_treelize_run(func, _l_args, _d_kwargs,
+                                mode, inherit, allow_missing, missing_func, delayed)
+
+cdef object _c_func_treelize_run(object func, list args, dict kwargs, _e_tree_mode mode, bool inherit,
+                                 bool allow_missing, object missing_func, bool delayed):
     cdef list ck_args = []
     cdef list ck_kwargs = []
     cdef bool has_tree = False
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     for v in args:
         if isinstance(v, TreeStorage):
             ck_args.append((v.detach(), True))
@@ -66,9 +86,17 @@ cdef object _c_func_treelize_run(object func, list args, dict kwargs,
         for i, (av, at) in enumerate(ck_args):
             if at:
                 try:
-                    _l_args.append(av[k])
+                    v = av[k]
+                    if delayed:
+                        _l_args.append((av, k, v))
+                    else:
+                        v = _c_undelay_data(av, k, v)
+                        _l_args.append(v)
                 except KeyError:
                     if allow_missing:
+                        if delayed:
+                            _l_args.append((None, None, _VALUE_IS_MISSING))
+                        else:
                             _l_args.append(_VALUE_IS_MISSING)
                     else:
                         raise KeyError("Missing is off, key {key} not found in {item}.".format(
@@ -76,7 +104,10 @@ cdef object _c_func_treelize_run(object func, list args, dict kwargs,
                         ))
             else:
                 if inherit:
-                    _l_args.append(av)
+                    if delayed:
+                        _l_args.append((None, None, av))
+                    else:
+                        _l_args.append(undelay(av))
                 else:
                     raise TypeError("Inherit is off, tree value expected but {type} found in args {index}.".format(
                         type=repr(type(av).__name__), index=repr(i),
@@ -86,9 +117,17 @@ cdef object _c_func_treelize_run(object func, list args, dict kwargs,
         for ak, av, at in ck_kwargs:
             if at:
                 try:
-                    _d_kwargs[ak] = av[k]
+                    v = av[k]
+                    if delayed:
+                        _d_kwargs[ak] = (av, k, v)
+                    else:
+                        v = _c_undelay_data(av, k, v)
+                        _d_kwargs[ak] = v
                 except KeyError:
                     if allow_missing:
+                        if delayed:
+                            _d_kwargs[ak] = (None, None, _VALUE_IS_MISSING)
+                        else:
                             _d_kwargs[ak] = _VALUE_IS_MISSING
                     else:
                         raise KeyError("Missing is off, key {key} not found in {item}.".format(
@@ -96,19 +135,27 @@ cdef object _c_func_treelize_run(object func, list args, dict kwargs,
                         ))
             else:
                 if inherit:
-                    _d_kwargs[ak] = av
+                    if delayed:
+                        _d_kwargs[ak] = (None, None, av)
+                    else:
+                        _d_kwargs[ak] = undelay(av)
                 else:
                     raise TypeError("Inherit is off, tree value expected but {type} found in args {index}.".format(
                         type=repr(type(av).__name__), index=repr(ak),
                     ))
 
+        if delayed:
+            _d_res[k] = delayed_partial(_c_wrap_func_treelize_run, func, _l_args, _d_kwargs,
+                                        mode, inherit, allow_missing, missing_func, delayed)
+        else:
             _d_res[k] = _c_func_treelize_run(func, _l_args, _d_kwargs,
-                                         mode, inherit, allow_missing, missing_func)
+                                             mode, inherit, allow_missing, missing_func, delayed)
 
     return TreeStorage(_d_res)
 
-def _w_subside_func(object value, bool dict_=True, bool list_=True, bool tuple_=True, bool inherit=True):
-    return _c_subside(value, dict_, list_, tuple_, inherit)[0]
+def _w_subside_func(object value, bool dict_=True, bool list_=True, bool tuple_=True, bool inherit=True,
+                    object mode='strict', object missing=MISSING_NOT_ALLOW, bool delayed=False):
+    return _c_subside(value, dict_, list_, tuple_, inherit, mode, missing, delayed)[0]
 
 def _w_rise_func(object tree, bool dict_=True, bool list_=True, bool tuple_=True, object template=None):
     return _c_rise(tree, dict_, list_, tuple_, template)
@@ -116,16 +163,18 @@ def _w_rise_func(object tree, bool dict_=True, bool list_=True, bool tuple_=True
 # runtime function
 def _w_func_treelize_run(*args, object __w_func, _e_tree_mode __w_mode, object __w_return_type,
                          bool __w_inherit, bool __w_allow_missing, object __w_missing_func,
-                         object __w_subside, object __w_rise, **kwargs):
+                         bool __w_delayed, object __w_subside, object __w_rise, **kwargs):
     cdef list _a_args = [(item._detach() if isinstance(item, TreeValue) else item) for item in args]
     cdef dict _a_kwargs = {k: (v._detach() if isinstance(v, TreeValue) else v) for k, v in kwargs.items()}
 
+    cdef dict _w_subside_cfg
     if __w_subside is not None:
-        _a_args = [_w_subside_func(item, **__w_subside) for item in _a_args]
-        _a_kwargs = {key: _w_subside_func(value, **__w_subside) for key, value in _a_kwargs.items()}
+        _w_subside_cfg = {'delayed': __w_delayed, **__w_subside}
+        _a_args = [_w_subside_func(item, **_w_subside_cfg) for item in _a_args]
+        _a_kwargs = {key: _w_subside_func(value, **_w_subside_cfg) for key, value in _a_kwargs.items()}
 
     cdef object _st_res = _c_func_treelize_run(__w_func, _a_args, _a_kwargs, __w_mode,
-                                               __w_inherit, __w_allow_missing, __w_missing_func)
+                                               __w_inherit, __w_allow_missing, __w_missing_func, __w_delayed)
 
     cdef object _o_res
     if __w_return_type is not None:
@@ -144,15 +193,10 @@ def _w_func_treelize_run(*args, object __w_func, _e_tree_mode __w_mode, object _
     else:
         return None
 
-MISSING_NOT_ALLOW = SingletonMark("missing_not_allow")
-
-cdef _c_common_value(object item):
+cdef object _c_common_value(object item):
     return item
 
-# build-time function
-cpdef object _d_func_treelize(object func, object mode, object return_type, bool inherit, object missing,
-                              object subside, object rise):
-    cdef _e_tree_mode _v_mode = _c_load_mode(mode)
+cdef inline tuple _c_missing_process(object missing):
     cdef bool allow_missing
     cdef object missing_func
     if missing is MISSING_NOT_ALLOW:
@@ -162,6 +206,16 @@ cpdef object _d_func_treelize(object func, object mode, object return_type, bool
         allow_missing = True
         missing_func = missing if callable(missing) else partial(_c_common_value, missing)
 
+    return allow_missing, missing_func
+
+# build-time function
+cpdef object _d_func_treelize(object func, object mode, object return_type, bool inherit, object missing,
+                              bool delayed, object subside, object rise):
+    cdef _e_tree_mode _v_mode = _c_load_mode(mode)
+    cdef bool allow_missing
+    cdef object missing_func
+    allow_missing, missing_func = _c_missing_process(missing)
+
     cdef object _v_subside, _v_rise
     if subside is not None and not isinstance(subside, dict):
         _v_subside = {} if subside else None
@@ -175,12 +229,12 @@ cpdef object _d_func_treelize(object func, object mode, object return_type, bool
     _c_check(_v_mode, return_type, inherit, allow_missing, missing_func)
     return partial(_w_func_treelize_run, __w_func=func, __w_mode=_v_mode, __w_return_type=return_type,
                    __w_inherit=inherit, __w_allow_missing=allow_missing, __w_missing_func=missing_func,
-                   __w_subside=_v_subside, __w_rise=_v_rise)
+                   __w_delayed=delayed, __w_subside=_v_subside, __w_rise=_v_rise)
 
 @cython.binding(True)
 cpdef object func_treelize(object mode='strict', object return_type=TreeValue,
                            bool inherit=True, object missing=MISSING_NOT_ALLOW,
-                           object subside=None, object rise=None):
+                           bool delayed=False, object subside=None, object rise=None):
     """
     Overview:
         Wrap a common function to tree-supported function.
@@ -191,6 +245,8 @@ cpdef object func_treelize(object mode='strict', object return_type=TreeValue,
         - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
         - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
             default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
+        - delayed (:obj:`bool`): Enable delayed mode or not, the calculation will be delayed when enabled, \
+            default is ``False``, which means to all the calculation at once.
         - subside (:obj:`Union[Mapping, bool, None]`): Subside enabled to function's arguments or not, \
             and subside configuration, default is `None` which means do not use subside. \
             When subside is `True`, it will use all the default arguments in `subside` function.
@@ -213,4 +269,4 @@ cpdef object func_treelize(object mode='strict', object return_type=TreeValue,
         >>> ssum(t1, t2)  # TreeValue({'a': 12, 'b': 24, 'x': {'c': 36, 'd': 9}})
     """
     return partial(_d_func_treelize, mode=mode, return_type=return_type,
-                   inherit=inherit, missing=missing, subside=subside, rise=rise)
+                   inherit=inherit, missing=missing, delayed=delayed, subside=subside, rise=rise)

treevalue/tree/func/func.py

@@ -12,7 +12,7 @@ TreeClassType_ = TypeVar("TreeClassType_", bound=TreeValue)
 
 
 def func_treelize(mode: str = 'strict', return_type: Optional[Type[TreeClassType_]] = TreeValue,
-                  inherit: bool = True, missing: Union[Any, Callable] = MISSING_NOT_ALLOW,
+                  inherit: bool = True, missing: Union[Any, Callable] = MISSING_NOT_ALLOW, delayed: bool = False,
                   subside: Union[Mapping, bool, None] = None, rise: Union[Mapping, bool, None] = None):
     """
     Overview:
@@ -21,9 +21,11 @@ def func_treelize(mode: str = 'strict', return_type: Optional[Type[TreeClassType
     Arguments:
         - mode (:obj:`str`): Mode of the wrapping, default is `strict`.
         - return_type (:obj:`Optional[Type[TreeClassType_]]`): Return type of the wrapped function, default is `TreeValue`.
-        - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
+        - inherit (:obj:`bool`): Allow inheriting in wrapped function, default is `True`.
         - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
             default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
+        - delayed (:obj:`bool`): Enable delayed mode or not, the calculation will be delayed when enabled, \
+            default is ``False``, which means to all the calculation at once.
         - subside (:obj:`Union[Mapping, bool, None]`): Subside enabled to function's arguments or not, \
             and subside configuration, default is `None` which means do not use subside. \
             When subside is `True`, it will use all the default arguments in `subside` function.
@@ -47,7 +49,7 @@ def func_treelize(mode: str = 'strict', return_type: Optional[Type[TreeClassType
     """
 
     def _decorator(func):
-        _treelized = _c_func_treelize(mode, return_type, inherit, missing, subside, rise)(func)
+        _treelized = _c_func_treelize(mode, return_type, inherit, missing, delayed, subside, rise)(func)
 
         @wraps(func)
         def _new_func(*args, **kwargs):
@@ -82,7 +84,7 @@ def method_treelize(mode: str = 'strict', return_type: Optional[Type[TreeClassTy
         - mode (:obj:`str`): Mode of the wrapping, default is `strict`.
         - return_type (:obj:`Optional[Type[TreeClassType_]]`): Return type of the wrapped function, \
             default is `AUTO_DETECT_RETURN_VALUE`, which means automatically use the decorated method's class.
-        - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
+        - inherit (:obj:`bool`): Allow inheriting in wrapped function, default is `True`.
         - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
             default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
         - subside (:obj:`Union[Mapping, bool, None]`): Subside enabled to function's arguments or not, \
@@ -154,7 +156,7 @@ def classmethod_treelize(mode: str = 'strict', return_type: Optional[Type[TreeCl
         - mode (:obj:`str`): Mode of the wrapping, default is `strict`.
         - return_type (:obj:`Optional[Type[TreeClassType_]]`): Return type of the wrapped function, \
             default is `AUTO_DETECT_RETURN_VALUE`, which means automatically use the decorated method's class.
-        - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
+        - inherit (:obj:`bool`): Allow inheriting in wrapped function, default is `True`.
         - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
             default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
         - subside (:obj:`Union[Mapping, bool, None]`): Subside enabled to function's arguments or not, \

treevalue/tree/general/general.py

@@ -147,13 +147,14 @@ def general_tree_value(base: Optional[Mapping[str, Any]] = None,
             return typetrans(self, clazz)
 
         @_decorate_method
-        def map(self, mapper):
+        def map(self, mapper, delayed=False):
             """
             Overview:
                 Do mapping on every value in this tree.
 
             Arguments:
                 - func (:obj:): Function for mapping
+                - delayed (:obj:`bool`): Enable delayed mode for this mapping.
 
             Returns:
                 - tree (:obj:`_TreeValue`): Mapped tree value object.
@@ -164,7 +165,7 @@ def general_tree_value(base: Optional[Mapping[str, Any]] = None,
                 >>> t.map(lambda: 1)        # FastTreeValue({'a': 1, 'b': 1, 'x': {'c': 1, 'd': 1}})
                 >>> t.map(lambda x, p: p)   # FastTreeValue({'a': ('a',), 'b': ('b',), 'x': {'c': ('x', 'c'), 'd': ('x', 'd')}})
             """
-            return mapping(self, mapper)
+            return mapping(self, mapper, delayed)
 
         @_decorate_method
         def mask(self, mask_: TreeValue, remove_empty: bool = True):
@@ -308,9 +309,8 @@ def general_tree_value(base: Optional[Mapping[str, Any]] = None,
         @classmethod
         @_decorate_method
         def func(cls, mode: str = 'strict', inherit: bool = True,
-                 missing: Union[Any, Callable] = MISSING_NOT_ALLOW,
-                 subside: Union[Mapping, bool, None] = None,
-                 rise: Union[Mapping, bool, None] = None):
+                 missing: Union[Any, Callable] = MISSING_NOT_ALLOW, delayed: bool = False,
+                 subside: Union[Mapping, bool, None] = None, rise: Union[Mapping, bool, None] = None):
             """
             Overview:
                 Wrap a common function to tree-supported function based on this type.
@@ -320,6 +320,8 @@ def general_tree_value(base: Optional[Mapping[str, Any]] = None,
                 - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
                 - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
                     default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
+                - delayed (:obj:`bool`): Enable delayed mode or not, the calculation will be delayed when enabled, \
+                    default is ``False``, which means to all the calculation at once.
                 - subside (:obj:`Union[Mapping, bool, None]`): Subside enabled to function's arguments or not, \
                     and subside configuration, default is `None` which means do not use subside. \
                     When subside is `True`, it will use all the default arguments in `subside` function.
@@ -343,7 +345,7 @@ def general_tree_value(base: Optional[Mapping[str, Any]] = None,
                 >>> ssum(1, 2)    # 3
                 >>> ssum(t1, t2)  # FastTreeValue({'a': 12, 'b': 24, 'x': {'c': 36, 'd': 9}})
             """
-            return func_treelize(mode, cls, inherit, missing, subside, rise)
+            return func_treelize(mode, cls, inherit, missing, delayed, subside, rise)
 
         @classmethod
         @_decorate_method

treevalue/tree/tree/__init__.py

@@ -4,4 +4,4 @@ from .graph import graphics
 from .io import loads, load, dumps, dump
 from .service import jsonify, clone, typetrans, walk
 from .structural import subside, union, rise
-from .tree import TreeValue
+from .tree import TreeValue, delayed

treevalue/tree/tree/flatten.pyx

@@ -6,15 +6,16 @@
 import cython
 
 from .tree cimport TreeValue
-from ..common.storage cimport TreeStorage
+from ..common.storage cimport TreeStorage, _c_undelay_data
 
 cdef void _c_flatten(TreeStorage st, tuple path, list res) except *:
     cdef dict data = st.detach()
     cdef tuple curpath
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     for k, v in data.items():
+        v = _c_undelay_data(data, k, v)
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
             _c_flatten(v, curpath, res)
@@ -47,8 +48,9 @@ cdef void _c_flatten_values(TreeStorage st, list res) except *:
     cdef dict data = st.detach()
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     for k, v in data.items():
+        v = _c_undelay_data(data, k, v)
         if isinstance(v, TreeStorage):
             _c_flatten_values(v, res)
         else:
@@ -75,8 +77,9 @@ cdef void _c_flatten_keys(TreeStorage st, tuple path, list res) except *:
     cdef tuple curpath
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     for k, v in data.items():
+        v = _c_undelay_data(data, k, v)
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
             _c_flatten_keys(v, curpath, res)

treevalue/tree/tree/functional.pxd

@@ -12,8 +12,9 @@ cdef object _c_no_arg(object func, object v, object p)
 cdef object _c_one_arg(object func, object v, object p)
 cdef object _c_two_args(object func, object v, object p)
 cdef object _c_wrap_mapping_func(object func)
-cdef TreeStorage _c_mapping(TreeStorage st, object func, tuple path)
-cpdef TreeValue mapping(TreeValue tree, object func)
+cdef object _c_delayed_mapping(object so, object func, tuple path, bool delayed)
+cdef TreeStorage _c_mapping(TreeStorage st, object func, tuple path, bool delayed)
+cpdef TreeValue mapping(TreeValue tree, object func, bool delayed= *)
 cdef TreeStorage _c_filter_(TreeStorage st, object func, tuple path, bool remove_empty)
 cpdef TreeValue filter_(TreeValue tree, object func, bool remove_empty= *)
 cdef object _c_mask(TreeStorage st, object sm, tuple path, bool remove_empty)

treevalue/tree/tree/functional.pyx

@@ -8,7 +8,9 @@ from functools import partial
 from libcpp cimport bool
 
 from .tree cimport TreeValue
-from ..common.storage cimport TreeStorage
+from ..common.delay cimport undelay
+from ..common.delay import delayed_partial
+from ..common.storage cimport TreeStorage, _c_undelay_data
 
 cdef inline object _c_no_arg(object func, object v, object p):
     return func()
@@ -33,24 +35,40 @@ cdef inline object _c_wrap_mapping_func(object func):
     else:
         return partial(_c_no_arg, func)
 
-cdef TreeStorage _c_mapping(TreeStorage st, object func, tuple path):
+cdef object _c_delayed_mapping(object so, object func, tuple path, bool delayed):
+    cdef object nso = undelay(so)
+    if isinstance(nso, TreeValue):
+        nso = nso._detach()
+
+    if isinstance(nso, TreeStorage):
+        return _c_mapping(nso, func, path, delayed)
+    else:
+        return func(nso, path)
+
+cdef TreeStorage _c_mapping(TreeStorage st, object func, tuple path, bool delayed):
     cdef dict _d_st = st.detach()
     cdef dict _d_res = {}
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     cdef tuple curpath
     for k, v in _d_st.items():
+        if not delayed:
+            v = _c_undelay_data(_d_st, k, v)
+
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
-            _d_res[k] = _c_mapping(v, func, curpath)
+            _d_res[k] = _c_mapping(v, func, curpath, delayed)
+        else:
+            if delayed:
+                _d_res[k] = delayed_partial(_c_delayed_mapping, v, func, curpath, delayed)
             else:
                 _d_res[k] = func(v, curpath)
 
     return TreeStorage(_d_res)
 
 @cython.binding(True)
-cpdef TreeValue mapping(TreeValue tree, object func):
+cpdef TreeValue mapping(TreeValue tree, object func, bool delayed=False):
     """
     Overview:
         Do mapping on every value in this tree.
@@ -80,17 +98,18 @@ cpdef TreeValue mapping(TreeValue tree, object func):
         >>> mapping(t, lambda: 1)        # TreeValue({'a': 1, 'b': 1, 'x': {'c': 1, 'd': 1}})
         >>> mapping(t, lambda x, p: p)   # TreeValue({'a': ('a',), 'b': ('b',), 'x': {'c': ('x', 'c'), 'd': ('x', 'd')}})
     """
-    return type(tree)(_c_mapping(tree._detach(), _c_wrap_mapping_func(func), ()))
+    return type(tree)(_c_mapping(tree._detach(), _c_wrap_mapping_func(func), (), delayed))
 
 cdef TreeStorage _c_filter_(TreeStorage st, object func, tuple path, bool remove_empty):
     cdef dict _d_st = st.detach()
     cdef dict _d_res = {}
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     cdef tuple curpath
     cdef TreeStorage curst
     for k, v in _d_st.items():
+        v = _c_undelay_data(_d_st, k, v)
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
             curst = _c_filter_(v, func, curpath, remove_empty)
@@ -148,9 +167,11 @@ cdef object _c_mask(TreeStorage st, object sm, tuple path, bool remove_empty):
     cdef tuple curpath
     cdef object curres
     for k, v in _d_st.items():
+        v = _c_undelay_data(_d_st, k, v)
         curpath = path + (k,)
         if _b_tree_mask:
             mv = _d_sm[k]
+            mv = _c_undelay_data(_d_sm, k, mv)
         else:
             mv = sm
 
@@ -194,10 +215,11 @@ cdef object _c_reduce(TreeStorage st, object func, tuple path, object return_typ
     cdef dict _d_kwargs = {}
 
     cdef str k
-    cdef object v
+    cdef object v, nv
     cdef tuple curpath
     cdef object curst
     for k, v in _d_st.items():
+        v = _c_undelay_data(_d_st, k, v)
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
             curst = _c_reduce(v, func, curpath, return_type)

treevalue/tree/tree/service.pyx

@@ -9,7 +9,7 @@ import cython
 from libcpp cimport bool
 
 from .tree cimport TreeValue
-from ..common.storage cimport TreeStorage
+from ..common.storage cimport TreeStorage, _c_undelay_data
 
 cdef object _keep_object(object obj):
     return obj
@@ -29,7 +29,7 @@ cpdef object jsonify(TreeValue val):
     Example:
         >>> jsonify(TreeValue({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}}))  # {'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}}
     """
-    return val._detach().jsondumpx(_keep_object, False)
+    return val._detach().jsondumpx(_keep_object, False, False)
 
 @cython.binding(True)
 cpdef TreeValue clone(TreeValue t, object copy_value=None):
@@ -50,10 +50,18 @@ cpdef TreeValue clone(TreeValue t, object copy_value=None):
         >>> t = TreeValue({'a': 1, 'b': 2, 'x': {'c': 3, 'd': 4}})
         >>> clone(t.x)  # TreeValue({'c': 3, 'd': 4})
     """
+    cdef bool need_copy
     if not callable(copy_value):
-        copy_value = copy.deepcopy if copy_value else _keep_object
+        if copy_value:
+            need_copy = True
+            copy_value = copy.deepcopy
+        else:
+            need_copy = False
+            copy_value = _keep_object
+    else:
+        need_copy = True
 
-    return type(t)(t._detach().deepcopyx(copy_value))
+    return type(t)(t._detach().deepcopyx(copy_value, not need_copy))
 
 @cython.binding(True)
 cpdef TreeValue typetrans(TreeValue t, object return_type):
@@ -87,9 +95,10 @@ def _p_walk(TreeStorage tree, object type_, tuple path, bool include_nodes):
 
     cdef dict data = tree.detach()
     cdef str k
-    cdef object v
+    cdef object v, nv
     cdef tuple curpath
     for k, v in data.items():
+        v = _c_undelay_data(data, k, v)
         curpath = path + (k,)
         if isinstance(v, TreeStorage):
             yield from _p_walk(v, type_, curpath, include_nodes)

treevalue/tree/tree/structural.pxd

@@ -11,10 +11,11 @@ cdef class _SubsideCall:
 cdef object _c_subside_process(tuple value, object it)
 cdef tuple _c_subside_build(object value, bool dict_, bool list_, bool tuple_)
 cdef void _c_subside_missing()
-cdef object _c_subside(object value, bool dict_, bool list_, bool tuple_, bool inherit)
+cdef object _c_subside(object value, bool dict_, bool list_, bool tuple_, bool inherit,
+                       object mode, object missing, bool delayed)
 cdef object _c_subside_keep_type(object t)
 cpdef object subside(object value, bool dict_= *, bool list_= *, bool tuple_= *,
-                     object return_type= *, bool inherit= *)
+                     object return_type= *, bool inherit= *, object mode= *, object missing= *, bool delayed= *)
 
 cdef object _c_rise_tree_builder(tuple p, object it)
 cdef tuple _c_rise_tree_process(object t)

treevalue/tree/tree/structural.pyx

@@ -6,13 +6,16 @@
 from itertools import chain
 
 import cython
+from hbutils.design import SingletonMark
 from libcpp cimport bool
 
 from .tree cimport TreeValue
-from ..common.storage cimport TreeStorage
-from ..func.cfunc cimport _c_func_treelize_run
+from ..common.storage cimport TreeStorage, _c_undelay_data
+from ..func.cfunc cimport _c_func_treelize_run, _c_missing_process
 from ..func.modes cimport _c_load_mode
 
+MISSING_NOT_ALLOW = SingletonMark("missing_not_allow")
+
 cdef object _c_subside_process(tuple value, object it):
     cdef type type_
     cdef list items
@@ -76,25 +79,29 @@ cdef tuple _c_subside_build(object value, bool dict_, bool list_, bool tuple_):
         else:
             return (object, None), (value,), ()
 
-STRICT = _c_load_mode('STRICT')
-
 cdef inline void _c_subside_missing():
     pass
 
-cdef object _c_subside(object value, bool dict_, bool list_, bool tuple_, bool inherit):
+cdef object _c_subside(object value, bool dict_, bool list_, bool tuple_, bool inherit,
+                       object mode, object missing, bool delayed):
     cdef object builder, _i_args, _i_types
     builder, _i_args, _i_types = _c_subside_build(value, dict_, list_, tuple_)
     cdef list args = list(_i_args)
 
+    cdef bool allow_missing
+    cdef object missing_func
+    allow_missing, missing_func = _c_missing_process(missing)
+
     return _c_func_treelize_run(_SubsideCall(builder), args, {},
-                                STRICT, inherit, False, _c_subside_missing), _i_types
+                                _c_load_mode(mode), inherit, allow_missing, missing_func, delayed), _i_types
 
 cdef inline object _c_subside_keep_type(object t):
     return t
 
 @cython.binding(True)
 cpdef object subside(object value, bool dict_=True, bool list_=True, bool tuple_=True,
-                     object return_type=None, bool inherit=True):
+                     object return_type=None, bool inherit=True,
+                     object mode='strict', object missing=MISSING_NOT_ALLOW, bool delayed=False):
     """
     Overview:
         Drift down the structures (list, tuple, dict) down to the tree's value.
@@ -108,6 +115,11 @@ cpdef object subside(object value, bool dict_=True, bool list_=True, bool tuple_
             will be auto detected when there is exactly one tree value type in this original value, \
             otherwise the default will be `TreeValue`.
         - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
+        - mode (:obj:`str`): Mode of the wrapping, default is `strict`.
+        - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
+            default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
+        - delayed (:obj:`bool`): Enable delayed mode or not, the calculation will be delayed when enabled, \
+            default is ``False``, which means to all the calculation at once.
 
     Returns:
         - return (:obj:`_TreeValue`): Subsided tree value.
@@ -132,7 +144,7 @@ cpdef object subside(object value, bool dict_=True, bool list_=True, bool tuple_
         >>> #}), all structures above the tree values are subsided to the bottom of the tree.
     """
     cdef object result, _i_types
-    result, _i_types = _c_subside(value, dict_, list_, tuple_, inherit)
+    result, _i_types = _c_subside(value, dict_, list_, tuple_, inherit, mode, missing, delayed)
 
     cdef object type_
     cdef set types
@@ -150,7 +162,8 @@ cpdef object subside(object value, bool dict_=True, bool list_=True, bool tuple_
     return type_(result)
 
 @cython.binding(True)
-def union(*trees, object return_type=None, bool inherit=True):
+def union(*trees, object return_type=None, bool inherit=True,
+          object mode='strict', object missing=MISSING_NOT_ALLOW, bool delayed=False):
     """
     Overview:
         Union tree values together.
@@ -158,7 +171,12 @@ def union(*trees, object return_type=None, bool inherit=True):
     Arguments:
         - trees (:obj:`_TreeValue`): Tree value objects.
         - return_type (:obj:`Optional[Type[_ClassType]]`): Return type of the wrapped function, default is `TreeValue`.
-        - inherit (:obj:`bool`): Allow inherit in wrapped function, default is `True`.
+        - inherit (:obj:`bool`): Allow inheriting in wrapped function, default is `True`.
+        - mode (:obj:`str`): Mode of the wrapping, default is `strict`.
+        - missing (:obj:`Union[Any, Callable]`): Missing value or lambda generator of when missing, \
+            default is `MISSING_NOT_ALLOW`, which means raise `KeyError` when missing detected.
+        - delayed (:obj:`bool`): Enable delayed mode or not, the calculation will be delayed when enabled, \
+            default is ``False``, which means to all the calculation at once.
 
     Returns:
         - result (:obj:`TreeValue`): Unionised tree value.
@@ -169,7 +187,7 @@ def union(*trees, object return_type=None, bool inherit=True):
         >>> union(t, tx)  # TreeValue({'a': (1, True), 'b': (2, False), 'x': {'c': (3, True), 'd': (4, False)}})
     """
     cdef object result, _i_types
-    result, _i_types = _c_subside(tuple(trees), True, True, True, inherit)
+    result, _i_types = _c_subside(tuple(trees), True, True, True, inherit, mode, missing, delayed)
 
     cdef object type_
     cdef list types
@@ -200,7 +218,7 @@ cdef object _c_rise_tree_builder(tuple p, object it):
 
 cdef tuple _c_rise_tree_process(object t):
     cdef str k
-    cdef object v
+    cdef object v, nv
     cdef list _l_items, _l_values
     cdef object _i_item, _i_value
     cdef dict detached
@@ -209,6 +227,7 @@ cdef tuple _c_rise_tree_process(object t):
         _l_items = []
         _l_values = []
         for k, v in detached.items():
+            v = _c_undelay_data(detached, k, v)
             _i_item, _i_value = _c_rise_tree_process(v)
             _l_items.append((k, _i_item))
             _l_values.append(_i_value)

treevalue/tree/tree/tree.pxd

 # distutils:language=c++
 # cython:language_level=3
 
+from libcpp cimport bool
+
+from ..common.delay cimport DelayedProxy
 from ..common.storage cimport TreeStorage
 
 cdef class TreeValue:
@@ -15,3 +18,11 @@ cdef class TreeValue:
 
 cdef str _prefix_fix(object text, object prefix)
 cdef object _build_tree(TreeStorage st, object type_, str prefix, dict id_pool, tuple path)
+
+cdef class DetachedDelayedProxy(DelayedProxy):
+    cdef DelayedProxy proxy
+    cdef readonly bool calculated
+    cdef object val
+
+    cpdef object value(self)
+    cpdef object fvalue(self)
\ No newline at end of file

treevalue/tree/tree/tree.pyx

@@ -7,7 +7,8 @@ from operator import itemgetter
 import cython
 from hbutils.design import SingletonMark
 
-from ..common.storage cimport TreeStorage, create_storage
+from ..common.delay cimport undelay, _c_delayed_partial, DelayedProxy
+from ..common.storage cimport TreeStorage, create_storage, _c_undelay_data
 from ...utils import format_tree
 
 _GET_NO_DEFAULT = SingletonMark('get_no_default')
@@ -385,7 +386,7 @@ cdef object _build_tree(TreeStorage st, object type_, str prefix, dict id_pool,
     cdef list children = []
 
     cdef str k, _t_prefix
-    cdef object v
+    cdef object v, nv
     cdef dict data
     cdef tuple curpath
     if nid in id_pool:
@@ -395,6 +396,7 @@ cdef object _build_tree(TreeStorage st, object type_, str prefix, dict id_pool,
         id_pool[nid] = path
         data = st.detach()
         for k, v in sorted(data.items()):
+            v = _c_undelay_data(data, k, v)
             curpath = path + (k,)
             _t_prefix = f'{k} --> '
             if isinstance(v, TreeStorage):
@@ -404,3 +406,67 @@ cdef object _build_tree(TreeStorage st, object type_, str prefix, dict id_pool,
 
     self_repr = _prefix_fix(self_repr, prefix)
     return self_repr, children
+
+cdef class DetachedDelayedProxy(DelayedProxy):
+    def __init__(self, DelayedProxy proxy):
+        self.proxy = proxy
+        self.calculated = False
+        self.val = None
+
+    cpdef object value(self):
+        if not self.calculated:
+            self.val = undelay(self.proxy, False)
+            self.calculated = True
+
+        return self.val
+
+    cpdef object fvalue(self):
+        cdef object v = self.value()
+        if isinstance(v, TreeValue):
+            v = v._detach()
+        return v
+
+@cython.binding(True)
+def delayed(func, *args, **kwargs):
+    r"""
+    Overview:
+        Use delayed function in treevalue.
+        The given ``func`` will not be called until its value is accessed, and \
+        it will be only called once, after that the delayed node will be replaced by the actual value.
+
+    Arguments:
+        - func: Delayed function.
+        - args: Positional arguments.
+        - kwargs: Key-word arguments.
+
+    Examples::
+        >>> from treevalue import TreeValue, delayed
+        >>>
+        >>> def f(x):
+        >>>     print('f is called, x is', x)
+        >>>     return x ** x
+        >>>
+        >>> t = TreeValue({'a': delayed(f, 2), 'x': delayed(f, 3)})
+        >>> t.a
+        f is called, x is 2
+        4
+        >>> t.x
+        f is called, x is 3
+        27
+        >>> t.a
+        4
+        >>> t.x
+        27
+        >>> t = TreeValue({'a': delayed(f, 2), 'x': delayed(f, 3)})
+        >>> print(t)
+        f is called, x is 2
+        f is called, x is 3
+        <TreeValue 0x7f0fb7f03198>
+        ├── a --> 4
+        └── x --> 27
+        >>> print(t)
+        <TreeValue 0x7f0fb7f03198>
+        ├── a --> 4
+        └── x --> 27
+    """
+    return DetachedDelayedProxy(_c_delayed_partial(func, args, kwargs))