QmlJS: Add CompletionContextFinder to allow context sensitive completion

The plan is to use this to reduce the number of applicable
completion options, for instance for enum completion or property
names.

Done-with: Erik Verbruggen

src/libs/qmljs/qmljscompletioncontextfinder.cpp

@@ -0,0 +1,157 @@
+#include "qmljscompletioncontextfinder.h"
+
+#include <QtCore/QDebug>
+#include <QtGui/QTextDocument>
+
+using namespace QmlJS;
+
+/*
+    Saves and restores the state of the global linizer. This enables
+    backtracking.
+
+    Identical to the defines in qmljslineinfo.cpp
+*/
+#define YY_SAVE() LinizerState savedState = yyLinizerState
+#define YY_RESTORE() yyLinizerState = savedState
+
+CompletionContextFinder::CompletionContextFinder(const QTextCursor &cursor)
+    : m_cursor(cursor)
+{
+    QTextBlock lastBlock = cursor.block();
+    if (lastBlock.next().isValid())
+        lastBlock = lastBlock.next();
+    initialize(cursor.document()->begin(), lastBlock);
+
+    int startTokenIndex = yyLinizerState.tokens.size() - 1;
+    for (; startTokenIndex >= 0; --startTokenIndex) {
+        const Token &token = yyLinizerState.tokens.at(startTokenIndex);
+        if (token.end() <= cursor.positionInBlock())
+            break;
+    }
+
+    getQmlObjectTypeName(startTokenIndex);
+}
+
+void CompletionContextFinder::getQmlObjectTypeName(int startTokenIndex)
+{
+    YY_SAVE();
+
+    int tokenIndex = findOpeningBrace(startTokenIndex);
+    if (tokenIndex != -1) {
+        --tokenIndex;
+
+        // can be one of
+        // A.B on c.d
+        // A.B
+
+        bool identifierExpected = true;
+        int i = tokenIndex;
+        forever {
+            if (i < 0) {
+                if (!readLine())
+                    break;
+                else
+                    i = yyLinizerState.tokens.size() - 1;
+            }
+
+            const Token &token = yyLinizerState.tokens.at(i);
+            if (!identifierExpected && token.kind == Token::Dot) {
+                identifierExpected = true;
+            } else if (token.kind == Token::Identifier) {
+                const QString idText = yyLine->mid(token.begin(), token.length);
+                if (identifierExpected) {
+                    m_qmlObjectTypeName.prepend(idText);
+                    identifierExpected = false;
+                } else if (idText == QLatin1String("on")) {
+                    m_qmlObjectTypeName.clear();
+                    identifierExpected = true;
+                } else {
+                    break;
+                }
+            } else {
+                break;
+            }
+
+            --i;
+        }
+    }
+
+    YY_RESTORE();
+}
+
+QStringList CompletionContextFinder::qmlObjectTypeName() const
+{
+    return m_qmlObjectTypeName;
+}
+
+int CompletionContextFinder::findOpeningBrace(int startTokenIndex)
+{
+    YY_SAVE();
+
+    if (startTokenIndex == -1)
+        readLine();
+
+    Token::Kind nestedClosing;
+    int nestingCount = 0;
+
+    for (int i = 0; i < BigRoof; ++i) {
+        if (i != 0 || startTokenIndex == -1)
+            startTokenIndex = yyLinizerState.tokens.size() - 1;
+
+        for (int t = startTokenIndex; t >= 0; --t) {
+            const Token &token = yyLinizerState.tokens.at(t);
+            switch (token.kind) {
+            case Token::LeftBrace:
+                if (nestingCount > 0) {
+                    if (nestedClosing == Token::RightBrace)
+                        --nestingCount;
+                } else {
+                    return t;
+                }
+                break;
+            case Token::LeftParenthesis:
+                if (nestingCount > 0) {
+                    if (nestedClosing == Token::RightParenthesis)
+                        --nestingCount;
+                } else {
+                    YY_RESTORE();
+                    return -1;
+                }
+                break;
+            case Token::LeftBracket:
+                if (nestingCount > 0) {
+                    if (nestedClosing == Token::RightBracket)
+                        --nestingCount;
+                } else {
+                    YY_RESTORE();
+                    return -1;
+                }
+                break;
+
+            case Token::RightBrace:
+            case Token::RightParenthesis:
+            case Token::RightBracket:
+                if (nestingCount == 0) {
+                    nestedClosing = token.kind;
+                    nestingCount = 1;
+                } else if (nestedClosing == token.kind) {
+                    ++nestingCount;
+                }
+                break;
+
+            default: break;
+            }
+        }
+
+        if (! readLine())
+            break;
+    }
+
+    YY_RESTORE();
+    return -1;
+}
+
+bool CompletionContextFinder::inQmlBindingRhs()
+{
+    return false;
+}