From 878bc0720181a2fb7afb95d9fd950f9e911443be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorbj=C3=B8rn=20Lindeijer?= <thorbjorn.lindeijer@nokia.com>
Date: Wed, 27 May 2009 14:32:09 +0200
Subject: [PATCH] Introduced a backwards scanner for finding expression under
cursor
The backwards scanner lazily tokenizes strings. This optimizes the
common case where scanning one or two lines is enough while at the same
time we extended the limit from 5 to 10 lines.
Reviewed-by: Roberto Raggi
---
src/libs/cplusplus/ExpressionUnderCursor.cpp | 175 +++++++++++--------
src/libs/cplusplus/ExpressionUnderCursor.h | 10 +-
src/libs/cplusplus/SimpleLexer.h | 7 +
3 files changed, 112 insertions(+), 80 deletions(-)
diff --git a/src/libs/cplusplus/ExpressionUnderCursor.cpp b/src/libs/cplusplus/ExpressionUnderCursor.cpp
index 53dc9b4f2d1..aab83d53772 100644
--- a/src/libs/cplusplus/ExpressionUnderCursor.cpp
+++ b/src/libs/cplusplus/ExpressionUnderCursor.cpp
@@ -36,13 +36,100 @@
using namespace CPlusPlus;
+namespace CPlusPlus {
+
+class BackwardsScanner
+{
+ enum { MAX_BLOCK_COUNT = 10 };
+
+public:
+ BackwardsScanner(const QTextCursor &cursor)
+ : _offset(0)
+ , _blocksTokenized(0)
+ , _block(cursor.block())
+ {
+ _tokenize.setSkipComments(true);
+ _text = _block.text().left(cursor.position() - cursor.block().position());
+ _tokens.append(_tokenize(_text, previousBlockState(_block)));
+ }
+
+ QList<SimpleToken> tokens() const { return _tokens; }
+
+ const SimpleToken &operator[](int i)
+ {
+ while (_offset + i < 0) {
+ _block = _block.previous();
+ if (_blocksTokenized == MAX_BLOCK_COUNT || !_block.isValid()) {
+ ++_offset;
+ _tokens.prepend(SimpleToken()); // sentinel
+ break;
+ } else {
+ ++_blocksTokenized;
+
+ QString blockText = _block.text();
+ _text.prepend(blockText);
+ QList<SimpleToken> adaptedTokens;
+ for (int i = 0; i < _tokens.size(); ++i) {
+ const SimpleToken &t = _tokens.at(i);
+ const int position = t.position() + blockText.length();
+ adaptedTokens.append(SimpleToken(t.kind(),
+ position,
+ t.length(),
+ _text.midRef(position, t.length())));
+ }
+
+ _tokens = _tokenize(blockText, previousBlockState(_block));
+ _offset += _tokens.size();
+ _tokens += adaptedTokens;
+ }
+ }
+
+ return _tokens.at(_offset + i);
+ }
+
+ int startPosition() const
+ { return _block.position(); }
+
+ const QString &text() const
+ { return _text; }
+
+ QString text(int begin, int end) const
+ {
+ const SimpleToken &firstToken = _tokens.at(begin + _offset);
+ const SimpleToken &lastToken = _tokens.at(end + _offset - 1);
+ return _text.mid(firstToken.begin(), lastToken.end() - firstToken.begin());
+ }
+
+ int previousBlockState(const QTextBlock &block)
+ {
+ const QTextBlock prevBlock = block.previous();
+ if (prevBlock.isValid()) {
+ int state = prevBlock.userState();
+
+ if (state != -1)
+ return state;
+ }
+ return 0;
+ }
+
+private:
+ QList<SimpleToken> _tokens;
+ int _offset;
+ int _blocksTokenized;
+ QTextBlock _block;
+ QString _text;
+ SimpleLexer _tokenize;
+};
+
+}
+
ExpressionUnderCursor::ExpressionUnderCursor()
{ }
ExpressionUnderCursor::~ExpressionUnderCursor()
{ }
-int ExpressionUnderCursor::startOfMatchingBrace(const QList<SimpleToken> &tk, int index)
+int ExpressionUnderCursor::startOfMatchingBrace(BackwardsScanner &tk, int index)
{
if (tk[index - 1].is(T_RPAREN)) {
int i = index - 1;
@@ -54,7 +141,7 @@ int ExpressionUnderCursor::startOfMatchingBrace(const QList<SimpleToken> &tk, in
} else if (tk[i].is(T_RPAREN))
--count;
--i;
- } while (count != 0 && i > -1);
+ } while (count != 0 && tk[i].isNot(T_EOF_SYMBOL));
} else if (tk[index - 1].is(T_RBRACKET)) {
int i = index - 1;
int count = 0;
@@ -65,7 +152,7 @@ int ExpressionUnderCursor::startOfMatchingBrace(const QList<SimpleToken> &tk, in
} else if (tk[i].is(T_RBRACKET))
--count;
--i;
- } while (count != 0 && i > -1);
+ } while (count != 0 && tk[i].isNot(T_EOF_SYMBOL));
} else if (tk[index - 1].is(T_GREATER)) {
int i = index - 1;
int count = 0;
@@ -76,13 +163,13 @@ int ExpressionUnderCursor::startOfMatchingBrace(const QList<SimpleToken> &tk, in
} else if (tk[i].is(T_GREATER))
--count;
--i;
- } while (count != 0 && i > -1);
+ } while (count != 0 && tk[i].isNot(T_EOF_SYMBOL));
}
return index;
}
-int ExpressionUnderCursor::startOfExpression(const QList<SimpleToken> &tk, int index)
+int ExpressionUnderCursor::startOfExpression(BackwardsScanner &tk, int index)
{
// tk is a reference to a const QList. So, don't worry about [] access.
// ### TODO implement multiline support. It should be pretty easy.
@@ -178,95 +265,37 @@ bool ExpressionUnderCursor::isAccessToken(const SimpleToken &tk)
} // switch
}
-int ExpressionUnderCursor::previousBlockState(const QTextBlock &block)
-{
- const QTextBlock prevBlock = block.previous();
- if (prevBlock.isValid()) {
- int state = prevBlock.userState();
-
- if (state != -1)
- return state;
- }
- return 0;
-}
-
-void ExpressionUnderCursor::init(const QTextCursor &cursor,
- QList<SimpleToken> *tokens,
- QString *text,
- int *startPosition)
-{
- enum { MAX_BLOCK_COUNT = 5 };
-
- QTextBlock block = cursor.block();
- QTextBlock initialBlock = block;
- for (int i = 0; i < MAX_BLOCK_COUNT; ++i) {
- if (! initialBlock.previous().isValid())
- break;
-
- initialBlock = initialBlock.previous();
- }
-
- QTextBlock it = initialBlock;
- for (; it.isValid(); it = it.next()) {
- QString textBlock = it.text();
-
- if (it == block)
- textBlock = textBlock.left(cursor.position() - cursor.block().position());
-
- text->append(textBlock);
-
- if (it == block)
- break;
-
- text->append(QLatin1Char('\n'));
- }
-
- SimpleLexer tokenize;
- tokenize.setSkipComments(true);
- tokens->append(tokenize(*text, previousBlockState(initialBlock)));
- tokens->prepend(SimpleToken()); // sentinel
-
- if (startPosition)
- *startPosition = initialBlock.position();
-}
-
QString ExpressionUnderCursor::operator()(const QTextCursor &cursor)
{
- QList<SimpleToken> tokens;
- QString text;
-
- init(cursor, &tokens, &text);
+ BackwardsScanner scanner(cursor);
_jumpedComma = false;
- const int i = startOfExpression(tokens, tokens.size());
- if (i == tokens.size())
+ const int initialSize = scanner.tokens().size();
+ const int i = startOfExpression(scanner, initialSize);
+ if (i == initialSize)
return QString();
- return text.mid(tokens.at(i).position(),
- tokens.last().position() + tokens.last().length()
- - tokens.at(i).position());
+ return scanner.text(i, initialSize);
}
int ExpressionUnderCursor::startOfFunctionCall(const QTextCursor &cursor)
{
- QList<SimpleToken> tokens;
QString text;
- int startPosition;
- init(cursor, &tokens, &text, &startPosition);
+ BackwardsScanner scanner(cursor);
- int index = tokens.size();
+ int index = scanner.tokens().size();
forever {
- const SimpleToken &tk = tokens.at(index - 1);
+ const SimpleToken &tk = scanner[index - 1];
if (tk.is(T_EOF_SYMBOL))
break;
else if (tk.is(T_LPAREN))
- return startPosition + tk.position();
+ return scanner.startPosition() + tk.position();
else if (tk.is(T_RPAREN)) {
- int matchingBrace = startOfMatchingBrace(tokens, index);
+ int matchingBrace = startOfMatchingBrace(scanner, index);
if (matchingBrace == index) // If no matching brace found
return -1;
diff --git a/src/libs/cplusplus/ExpressionUnderCursor.h b/src/libs/cplusplus/ExpressionUnderCursor.h
index dda77c406c5..1214d08902d 100644
--- a/src/libs/cplusplus/ExpressionUnderCursor.h
+++ b/src/libs/cplusplus/ExpressionUnderCursor.h
@@ -41,6 +41,7 @@ QT_END_NAMESPACE
namespace CPlusPlus {
+class BackwardsScanner;
class SimpleToken;
class CPLUSPLUS_EXPORT ExpressionUnderCursor
@@ -53,13 +54,8 @@ public:
int startOfFunctionCall(const QTextCursor &cursor);
private:
- void init(const QTextCursor &cursor,
- QList<SimpleToken> *tokens,
- QString *text,
- int *startPosition = 0);
-
- int startOfMatchingBrace(const QList<SimpleToken> &tk, int index);
- int startOfExpression(const QList<SimpleToken> &tk, int index);
+ int startOfMatchingBrace(BackwardsScanner &tk, int index);
+ int startOfExpression(BackwardsScanner &tk, int index);
int previousBlockState(const QTextBlock &block);
bool isAccessToken(const SimpleToken &tk);
diff --git a/src/libs/cplusplus/SimpleLexer.h b/src/libs/cplusplus/SimpleLexer.h
index 0366738c6bd..666478016a7 100644
--- a/src/libs/cplusplus/SimpleLexer.h
+++ b/src/libs/cplusplus/SimpleLexer.h
@@ -41,6 +41,13 @@ class SimpleLexer;
class CPLUSPLUS_EXPORT SimpleToken
{
public:
+ SimpleToken(int kind, int position, int length, const QStringRef &text)
+ : _kind(kind)
+ , _position(position)
+ , _length(length)
+ , _text(text)
+ { }
+
SimpleToken()
: _kind(0),
_position(0),
--
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