From f075141b9144b6fdb91ccc2af9216601d70568c5 Mon Sep 17 00:00:00 2001
From: Zhuoyuan <chenzhuoyuan07@gmail.com>
Date: Mon, 28 Aug 2017 11:37:49 -0700
Subject: [PATCH] switch_op.cc

---
 paddle/operators/switch_op.cc | 120 ++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 paddle/operators/switch_op.cc

diff --git a/paddle/operators/switch_op.cc b/paddle/operators/switch_op.cc
new file mode 100644
index 00000000000..09574a89a35
--- /dev/null
+++ b/paddle/operators/switch_op.cc
@@ -0,0 +1,120 @@
+#include "paddle/operators/switch_op.h"
+
+namespace paddle {
+namespace operators {
+
+// namespace if_else{
+
+
+void CondOp::Init() override {
+}
+
+void InferShape(const std::shared_ptr<Scope>& scope) const override {
+  subnet_t = GetAttr<std::string>("subnet_t");
+  subnet_f = GetAttr<std::string>("subnet_f");
+
+  // Create two Nets
+  // I use the same style as Recurrent_op, but does it create the net?
+  // can be called like
+  Variable* net_t = scope.FindVar(subnet_t);
+  Variable* net_f = scope.FindVar(subnet_f);
+
+  net_op_t = scope.FindVar(net_t)->GetMutable<NetOp>();
+  net_op_f = scope.FindVar(net_f)->GetMutable<NetOp>();
+
+  // Create two scopes
+  scope_t = scope.NewScope();
+  scope_f = scope.NewScope();
+
+  // check cond of size (batch_size), type bool
+  net_op_t->InferShape(scope_t);
+  net_op_f->InferShape(scope_f);
+
+  // check net_op_t and net_op_f of exactly same shape?
+}
+
+void IfElseOp::Run(const std::shared_ptr<Scope>& scope,
+                   const platform::DeviceContext& dev_ctx) const {
+  /* step 1: create two subnets and scopes, supposed done in Infershape() */
+
+  /* step 2: get true and false index */
+  cond = Input(name.cond);
+  // get condition tensor
+  auto cond_tensor = scope.get<Tensor>(cond);
+  // tensor to cpu, whatever device it used to be in
+  cond_cpu.CopyFrom(cond_tensor, platform::CPUPlace());
+
+  size_t batch_size = cond_cpu.dims()[0];
+
+  // keep index of true and false to slice, clear them first before each batch
+  true_index.clear();
+  false_index.clear();
+  	
+  // get a DDim type variable dims, check dimension
+  auto dims = input0.dims();
+  for(int i=0; i<dims; i++) {
+    if (cond_cpu->data[i])
+      true_index.push_back(i);
+    else
+      false_index.push_back(i);
+  }
+
+  // turn true_index and false_index to tensors
+  Tensor* true_index_tensor = new Tensor(true_index);
+  Tensor* false_index_tensor = new Tensor(false_index);
+
+  /* Step 3: Gather */
+  { // True Scope
+    // Create new stuff
+    for (auto& input : net_op_t->inputs_) {
+      scope_t.NewVar(input);
+      if (input.type() != PARAMETER) { // gather and slice required
+        // Get Tensor and gather
+        Tensor* input_gather_ = scope_t.FindVar(input)->GetMutable<Tensor>();
+        Tensor* input_full_ = scope.FindVar(input)->GetMutable<Tensor>();
+        input_gather_ = Gather(input_full_, true_index_tensor);
+      }
+    }
+
+    for (auto& output : net_op->outputs_) {
+      scope_t.NewVar(output);
+    }
+      
+    net_op_t.Run();
+  }
+
+  { // False Scope
+    // Create new stuff
+    for (auto& input : net_op_f->inputs_) {
+      scope_f.NewVar(input);
+      if (input.type() != PARAMETER) { // gather and slice required
+        // Get Tensor and gather
+        Tensor* input_gather_ = scope_f.FindVar(input)->GetMutable<Tensor>();
+        Tensor* input_full_ = scope.FindVar(input)->GetMutable<Tensor>();
+        input_gather_ = Gather(input_full_, false_index_tensor);
+      }
+    }
+
+    for (auto& output : net_op->outputs_) {
+      scope_t.NewVar(output);
+    }
+
+    net_op_f.Run();
+  }
+
+  /* Merge Output Together by scatter update */
+  for (auto& ouput : outputs_) {
+    Tensor* output_t = scope_t->FindVar(output)->GetMutable<Tensor>();
+    Tensor* output_f = scope_f->FindVar(output)->GetMutable<Tensor>();
+    Tensor* output_tensor = scope->FindVar(output)->GetMutable<Tensor>();
+    Scatter(output_t, output_tensor, true_index_tensor);
+    Scatter(output_f, output_tensor, false_index_tensor);
+  }
+}
+
+}  // namespace operators
+}  // namespace paddle
+
+REGISTER_OP(ifelse_op,
+            paddle::operators::IfElseOp,
+            paddle::operators::RecurrentAlgorithmProtoAndCheckerMaker);
-- 
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