Add help IsValid* methods to string classeschromium/3198chromium/3197

The various string classes, CFX_ByteString, CFX_ByteStringC,
CFX_WideString, and CFX_WideStringC, have many conditionals that are
effectively determining if a value is a valid index or length. This CL
refactors the logic into one place per class, so it only needs to be
changed once if its behaviour needs to change. It also make the some
of the methods stricter on the inputs they will accept.

BUG=pdfium:828

Change-Id: Iadcdaa34a6d862a2804485770027179c89dc6956
Reviewed-on: https://pdfium-review.googlesource.com/12030
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 20 insertions, 27 deletions

diff --git a/core/fxcrt/cfx_bytestring_unittest.cpp b/core/fxcrt/cfx_bytestring_unittest.cpp
index e7281546fb..497e0b6c2f 100644
--- a/core/fxcrt/cfx_bytestring_unittest.cpp
+++ b/core/fxcrt/cfx_bytestring_unittest.cpp
@@ -291,7 +291,7 @@ TEST(fxcrt, ByteStringOperatorNE) {
 TEST(fxcrt, ByteStringCNull) {
   CFX_ByteStringC null_string;
   EXPECT_FALSE(null_string.raw_str());
-  EXPECT_EQ(null_string.GetLength(), 0);
+  EXPECT_EQ(0, null_string.GetLength());
   EXPECT_TRUE(null_string.IsEmpty());
 
   CFX_ByteStringC another_null_string;
@@ -299,27 +299,27 @@ TEST(fxcrt, ByteStringCNull) {
 
   CFX_ByteStringC copied_null_string(null_string);
   EXPECT_FALSE(copied_null_string.raw_str());
-  EXPECT_EQ(copied_null_string.GetLength(), 0);
+  EXPECT_EQ(0, copied_null_string.GetLength());
   EXPECT_TRUE(copied_null_string.IsEmpty());
   EXPECT_EQ(null_string, copied_null_string);
 
   CFX_ByteStringC empty_string("");  // Pointer to NUL, not NULL pointer.
   EXPECT_TRUE(empty_string.raw_str());
-  EXPECT_EQ(empty_string.GetLength(), 0);
+  EXPECT_EQ(0, empty_string.GetLength());
   EXPECT_TRUE(empty_string.IsEmpty());
   EXPECT_EQ(null_string, empty_string);
 
   CFX_ByteStringC assigned_null_string("initially not nullptr");
   assigned_null_string = null_string;
   EXPECT_FALSE(assigned_null_string.raw_str());
-  EXPECT_EQ(assigned_null_string.GetLength(), 0);
+  EXPECT_EQ(0, assigned_null_string.GetLength());
   EXPECT_TRUE(assigned_null_string.IsEmpty());
   EXPECT_EQ(null_string, assigned_null_string);
 
   CFX_ByteStringC assigned_nullptr_string("initially not nullptr");
   assigned_nullptr_string = nullptr;
   EXPECT_FALSE(assigned_nullptr_string.raw_str());
-  EXPECT_EQ(assigned_nullptr_string.GetLength(), 0);
+  EXPECT_EQ(0, assigned_nullptr_string.GetLength());
   EXPECT_TRUE(assigned_nullptr_string.IsEmpty());
   EXPECT_EQ(null_string, assigned_nullptr_string);
 
@@ -345,13 +345,6 @@ TEST(fxcrt, ByteStringConcat) {
   fred.Concat("DY", 2);
   EXPECT_EQ("FREDDY", fred);
   EXPECT_EQ("FRED", copy);
-
-  // Test invalid arguments.
-  copy = fred;
-  fred.Concat("freddy", -6);
-  CFX_ByteString not_aliased("xxxxxx");
-  EXPECT_EQ("FREDDY", fred);
-  EXPECT_EQ("xxxxxx", not_aliased);
 }
 
 TEST(fxcrt, ByteStringRemove) {
@@ -524,10 +517,10 @@ TEST(fxcrt, ByteStringMid) {
   EXPECT_EQ("D", fred.Mid(3, 1));
   EXPECT_EQ("FR", fred.Mid(0, 2));
   EXPECT_EQ("FRED", fred.Mid(0, 4));
-  EXPECT_EQ("FRED", fred.Mid(0, 10));
+  EXPECT_EQ("", fred.Mid(0, 10));
 
-  EXPECT_EQ("FR", fred.Mid(-1, 2));
-  EXPECT_EQ("RED", fred.Mid(1, 4));
+  EXPECT_EQ("", fred.Mid(-1, 2));
+  EXPECT_EQ("RED", fred.Mid(1, 3));
   EXPECT_EQ("", fred.Mid(4, 1));
 
   CFX_ByteString empty;
@@ -542,7 +535,7 @@ TEST(fxcrt, ByteStringLeft) {
   EXPECT_EQ("FRE", fred.Left(3));
   EXPECT_EQ("FRED", fred.Left(4));
 
-  EXPECT_EQ("FRED", fred.Left(5));
+  EXPECT_EQ("", fred.Left(5));
   EXPECT_EQ("", fred.Left(-1));
 
   CFX_ByteString empty;
@@ -559,7 +552,7 @@ TEST(fxcrt, ByteStringRight) {
   EXPECT_EQ("RED", fred.Right(3));
   EXPECT_EQ("FRED", fred.Right(4));
 
-  EXPECT_EQ("FRED", fred.Right(5));
+  EXPECT_EQ("", fred.Right(5));
   EXPECT_EQ("", fred.Right(-1));
 
   CFX_ByteString empty;
@@ -1004,31 +997,31 @@ TEST(fxcrt, ByteStringCMid) {
   EXPECT_EQ(null_string, null_string.Mid(1, 1));
 
   CFX_ByteStringC empty_string("");
-  EXPECT_EQ(empty_string, empty_string.Mid(0, 1));
-  EXPECT_EQ(empty_string, empty_string.Mid(1, 1));
+  EXPECT_EQ("", empty_string.Mid(0, 1));
+  EXPECT_EQ("", empty_string.Mid(1, 1));
 
   CFX_ByteStringC single_character("a");
-  EXPECT_EQ(empty_string, single_character.Mid(0, 0));
+  EXPECT_EQ("", single_character.Mid(0, 0));
   EXPECT_EQ(single_character, single_character.Mid(0, 1));
-  EXPECT_EQ(empty_string, single_character.Mid(1, 0));
-  EXPECT_EQ(empty_string, single_character.Mid(1, 1));
+  EXPECT_EQ("", single_character.Mid(1, 0));
+  EXPECT_EQ("", single_character.Mid(1, 1));
 
   CFX_ByteStringC longer_string("abcdef");
   EXPECT_EQ(longer_string, longer_string.Mid(0, 6));
-  EXPECT_EQ(longer_string, longer_string.Mid(0, 187));
-  EXPECT_EQ(longer_string, longer_string.Mid(-42, 6));
-  EXPECT_EQ(longer_string, longer_string.Mid(-42, 187));
+  EXPECT_EQ("", longer_string.Mid(0, 187));
+  EXPECT_EQ("", longer_string.Mid(-42, 6));
+  EXPECT_EQ("", longer_string.Mid(-42, 187));
 
   CFX_ByteStringC leading_substring("ab");
   EXPECT_EQ(leading_substring, longer_string.Mid(0, 2));
-  EXPECT_EQ(leading_substring, longer_string.Mid(-1, 2));
+  EXPECT_EQ("", longer_string.Mid(-1, 2));
 
   CFX_ByteStringC middle_substring("bcde");
   EXPECT_EQ(middle_substring, longer_string.Mid(1, 4));
 
   CFX_ByteStringC trailing_substring("ef");
   EXPECT_EQ(trailing_substring, longer_string.Mid(4, 2));
-  EXPECT_EQ(trailing_substring, longer_string.Mid(4, 3));
+  EXPECT_EQ("", longer_string.Mid(4, 3));
 }
 
 TEST(fxcrt, ByteStringCElementAccess) {