QDoc: Remove `QmlCodeParser::m_lexer`

As part of producing a documentation set, QDoc parses a series of
user-defined input source files in various languages to extract the
user-provided documentation and certain source-code level elements.

For QML source files, the `QmlCodeParser` class is used, taking care of
reading the QML code and build an internal representation for some of
its elements.

`QmlCodeParser` uses the `QQmlJs` parsing api to do so.
As part of using the `QQmlJs` parsing api, `QmlCodeParser` has to build
a `QQmlJs::Engine`, `QQmlJs::Lexer` and `QQmlJsEngine::Parser`.

Currently, `QmlCodeParser` stores all those elements as instance
members. For example, for the `QQmlJs::Lexer` instance, a member
variable `m_lexer` is used as storage.
Supposedly, this is intended as a way to avoid building the three
elements more than once.

Building a `QQmlJs::Lexer` more than once does not provide any
meaningful overhead, moreover not in the code path where it is used.
Furthermore, `m_lexer` is used only once, in
`QmlCodeParser::parseSourceFile`, the entry point for parsing a QML
source file.

Hence, to reduce the scope of `m_lexer` and avoid requiring an
out-of-scope initialization for it, `m_lexer` is now removed in favor of
an local instance in `QmlCodeParser::parseSourceFile`.

The initialization and deletion of `m_lexer` in
`QmlCodeParser::initializeParser` and `QmlCodeParser::terminateParser`
was removed as a consequence of the removal of the member.

Some comments that mentioned the initialization or deletion of the lexer
were modified to represent the modified code.

Change-Id: I32d38e7883273ab83745eb1f34d183fd5ecca19a
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 0 insertions, 1 deletions

diff --git a/src/qdoc/qmlcodeparser.h b/src/qdoc/qmlcodeparser.h
index 91ee64858..bbf2a1545 100644
--- a/src/qdoc/qmlcodeparser.h
+++ b/src/qdoc/qmlcodeparser.h
@@ -34,7 +34,6 @@ public:
 
 private:
     QQmlJS::Engine m_engine {};
-    QQmlJS::Lexer *m_lexer { nullptr };
     QQmlJS::Parser *m_parser { nullptr };
 };