From 69fee6812b756a8ca4866038d4ff866eccc2f303 Mon Sep 17 00:00:00 2001
From: chertus <chertus@gmail.com>
Date: Tue, 21 Jan 2020 21:04:22 +0300
Subject: [PATCH] variant without catch

---
 dbms/src/IO/readDecimalText.h                 | 46 ++++++++++++-------
 .../01070_to_decimal_or_null_exception.sql    |  6 +--
 2 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/dbms/src/IO/readDecimalText.h b/dbms/src/IO/readDecimalText.h
index 045cc38736..5b2a3f7648 100644
--- a/dbms/src/IO/readDecimalText.h
+++ b/dbms/src/IO/readDecimalText.h
@@ -11,8 +11,8 @@ namespace ErrorCodes
 }
 
 
-template <typename T>
-inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exponent, bool digits_only = false)
+template <bool _throw_on_error, typename T>
+inline bool readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exponent, bool digits_only = false)
 {
     x = 0;
     exponent = 0;
@@ -24,7 +24,11 @@ inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exp
     bool after_point = false;
 
     if (buf.eof())
-        throwReadAfterEOF();
+    {
+        if constexpr (_throw_on_error)
+            throwReadAfterEOF();
+        return false;
+    }
 
     if (!buf.eof())
     {
@@ -75,8 +79,12 @@ inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exp
 
                 ++places; // num zeroes before + current digit
                 if (digits + places > max_digits)
-                    throw Exception("Too many digits (" + std::to_string(digits + places) + " > " + std::to_string(max_digits)
+                {
+                    if constexpr (_throw_on_error)
+                        throw Exception("Too many digits (" + std::to_string(digits + places) + " > " + std::to_string(max_digits)
                             + ") in decimal value", ErrorCodes::ARGUMENT_OUT_OF_BOUND);
+                    return false;
+                }
 
                 digits += places;
                 if (after_point)
@@ -93,7 +101,13 @@ inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exp
             {
                 ++buf.position();
                 Int32 addition_exp = 0;
-                readIntText(addition_exp, buf);
+                if (!tryReadIntText(addition_exp, buf))
+                {
+                    if constexpr (_throw_on_error)
+                        throw Exception("Cannot parse exponent while reading decimal", ErrorCodes::CANNOT_PARSE_NUMBER);
+                    else
+                        return false;
+                }
                 exponent += addition_exp;
                 stop = true;
                 continue;
@@ -101,7 +115,11 @@ inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exp
 
             default:
                 if (digits_only)
-                    throw Exception("Unexpected symbol while reading decimal", ErrorCodes::CANNOT_PARSE_NUMBER);
+                {
+                    if constexpr (_throw_on_error)
+                        throw Exception("Unexpected symbol while reading decimal", ErrorCodes::CANNOT_PARSE_NUMBER);
+                    return false;
+                }
                 stop = true;
                 continue;
         }
@@ -109,6 +127,7 @@ inline void readDigits(ReadBuffer & buf, T & x, unsigned int & digits, int & exp
     }
 
     x *= sign;
+    return true;
 }
 
 template <typename T>
@@ -116,7 +135,7 @@ inline void readDecimalText(ReadBuffer & buf, T & x, unsigned int precision, uns
 {
     unsigned int digits = precision;
     int exponent;
-    readDigits(buf, x, digits, exponent, digits_only);
+    readDigits<true>(buf, x, digits, exponent, digits_only);
 
     if (static_cast<int>(digits) + exponent > static_cast<int>(precision - scale))
         throw Exception("Decimal value is too big", ErrorCodes::ARGUMENT_OUT_OF_BOUND);
@@ -132,17 +151,10 @@ inline bool tryReadDecimalText(ReadBuffer & buf, T & x, unsigned int precision,
     unsigned int digits = precision;
     int exponent;
 
-    try
-    {
-        readDigits(buf, x, digits, exponent, true);
-        if (static_cast<int>(digits) + exponent > static_cast<int>(precision - scale) ||
-            static_cast<int>(scale) + exponent < 0)
-            return false;
-    }
-    catch (const Exception &)
-    {
+    if (!readDigits<false>(buf, x, digits, exponent, true) ||
+        static_cast<int>(digits) + exponent > static_cast<int>(precision - scale) ||
+        static_cast<int>(scale) + exponent < 0)
         return false;
-    }
 
     scale += exponent;
     return true;
diff --git a/dbms/tests/queries/0_stateless/01070_to_decimal_or_null_exception.sql b/dbms/tests/queries/0_stateless/01070_to_decimal_or_null_exception.sql
index 691d117ac5..9283cc76cd 100644
--- a/dbms/tests/queries/0_stateless/01070_to_decimal_or_null_exception.sql
+++ b/dbms/tests/queries/0_stateless/01070_to_decimal_or_null_exception.sql
@@ -1,6 +1,6 @@
-SELECT toDecimal32('e', 1); -- { serverError 32 }
-SELECT toDecimal64('e', 2); -- { serverError 32 }
-SELECT toDecimal128('e', 3); -- { serverError 32 }
+SELECT toDecimal32('e', 1); -- { serverError 72 }
+SELECT toDecimal64('e', 2); -- { serverError 72 }
+SELECT toDecimal128('e', 3); -- { serverError 72 }
 
 SELECT toDecimal32OrNull('e', 1) x, isNull(x);
 SELECT toDecimal64OrNull('e', 2) x, isNull(x);
-- 
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