Changeset 219285 in webkit for trunk/Source/JavaScriptCore/parser/Lexer.cpp

Timestamp:

Jul 9, 2017, 7:34:55 PM (8 years ago)

Author:

Yusuke Suzuki

Message:

[JSC] Drop LineNumberAdder since we no longer treat <LF><CR> (not <CR><LF>) as one line terminator
​https://bugs.webkit.org/show_bug.cgi?id=174296

Reviewed by Mark Lam.

Previously, we treat <LF><CR> as one line terminator. So we increase line number by one.
It caused a problem in scanning template literals. While template literals normalize
<LF><CR> to <LF><LF>, we still needed to increase line number by only one.
To handle it correctly, LineNumberAdder is introduced.

As of r219263, <LF><CR> is counted as two line terminators. So we do not need to have
LineNumberAdder. Let's just use shiftLineTerminator() instead.

• parser/Lexer.cpp:

(JSC::Lexer<T>::parseTemplateLiteral):
(JSC::LineNumberAdder::LineNumberAdder): Deleted.
(JSC::LineNumberAdder::clear): Deleted.
(JSC::LineNumberAdder::add): Deleted.

File:

• trunk/Source/JavaScriptCore/parser/Lexer.cpp (modified) (6 diffs)

trunk/Source/JavaScriptCore/parser/Lexer.cpp

@@ -1376 +1376 @@
 }
 
-// While the lexer accepts <LF><CR> (not <CR><LF>) sequence
-// as one line terminator and increments one line number,
-// TemplateLiteral considers it as two line terminators <LF> and <CR>.
-//
-// TemplateLiteral normalizes line terminators as follows.
-//
-// <LF> => <LF>
-// <CR> => <LF>
-// <CR><LF> => <LF>
-// <\u2028> => <\u2028>
-// <\u2029> => <\u2029>
-//
-// So, <LF><CR> should be normalized to <LF><LF>.
-// However, the lexer should increment the line number only once for <LF><CR>.
-//
-// To achieve this, LineNumberAdder holds the current status of line terminator sequence.
-// When TemplateLiteral lexer encounters a line terminator, it notifies to LineNumberAdder.
-// LineNumberAdder maintains the status and increments the line number when it's necessary.
-// For example, LineNumberAdder increments the line number only once for <LF><CR> and <CR><LF>.
-template<typename CharacterType>
-class LineNumberAdder {
-public:
-    LineNumberAdder(int& lineNumber)
-        : m_lineNumber(lineNumber)
-    {
-    }
-
-    void clear()
-    {
-        m_previous = 0;
-    }
-
-    void add(CharacterType character)
-    {
-        ASSERT(Lexer<CharacterType>::isLineTerminator(character));
-        if (m_previous == '\r' && character == '\n')
-            m_previous = 0;
-        else {
-            ++m_lineNumber;
-            m_previous = character;
-        }
-    }
-
-private:
-    int& m_lineNumber;
-    CharacterType m_previous { 0 };
-};
-
 template <typename T>
 typename Lexer<T>::StringParseResult Lexer<T>::parseTemplateLiteral(JSTokenData* tokenData, RawStringsBuildMode rawStringsBuildMode)
@@ -1431 +1383 @@
     const T* rawStringStart = currentSourcePtr();
 
-    LineNumberAdder<T> lineNumberAdder(m_lineNumber);
-
     while (m_current != '`') {
         if (UNLIKELY(m_current == '\\')) {
-            lineNumberAdder.clear();
             if (stringStart != currentSourcePtr())
                 append16(stringStart, currentSourcePtr() - stringStart);
@@ -1456 +1405 @@
                     }
 
-                    lineNumberAdder.add(m_current);
-                    shift();
-                    if (m_current == '\n') {
-                        lineNumberAdder.add(m_current);
-                        shift();
-                    }
-
+                    shiftLineTerminator();
                     rawStringStart = currentSourcePtr();
-                } else {
-                    lineNumberAdder.add(m_current);
-                    shift();
-                }
+                } else
+                    shiftLineTerminator();
             } else {
                 bool strictMode = true;
@@ -1494 +1435 @@
             if (atEnd()) {
                 m_lexErrorMessage = ASCIILiteral("Unexpected EOF");
-                return atEnd() ? StringUnterminated : StringCannotBeParsed;
+                return StringUnterminated;
             }
 
@@ -1508 +1449 @@
                     if (rawStringsBuildMode == RawStringsBuildMode::BuildRawStrings)
                         m_bufferForRawTemplateString16.append('\n');
-                    lineNumberAdder.add(m_current);
-                    shift();
-                    if (m_current == '\n') {
-                        lineNumberAdder.add(m_current);
-                        shift();
-                    }
+                    shiftLineTerminator();
                     stringStart = currentSourcePtr();
                     rawStringStart = currentSourcePtr();
-                } else {
-                    lineNumberAdder.add(m_current);
-                    shift();
-                }
+                } else
+                    shiftLineTerminator();
                 continue;
             }
@@ -1525 +1459 @@
         }
 
-        lineNumberAdder.clear();
         shift();
     }