[PATCH v3 2/4] [gdb/cli] Factor out try_source_highlight

Tom de Vries
2023-10-16T09:17:48Z

Function source_cache::ensure contains some code using the GNU
source-highlight library.

The code is a sizable part of the function, and contains conditional
compilation in a slightly convoluted way:
...
if (!already_styled)
#endif /* HAVE_SOURCE_HIGHLIGHT */
{
...

Fix this by factoring out the code into new function try_source_highlight,
such that:
- source_cache::ensure is easier to read, and
- the conditional compilation is at the level of the function body.

Tested on x86_64-linux.
---
gdb/source-cache.c | 91 ++++++++++++++++++++++++++++------------------
1 file changed, 55 insertions(+), 36 deletions(-)

diff --git a/gdb/source-cache.c b/gdb/source-cache.c
index ae02d2516d9..191d0043e66 100644
--- a/gdb/source-cache.c
+++ b/gdb/source-cache.c
@@ -191,6 +191,59 @@ get_language_name (enum language lang)

#endif /* HAVE_SOURCE_HIGHLIGHT */

+/* Try to highlight CONTENTS from file FULLNAME in language LANG using
+ the GNU source-higlight library. Return true if highlighting
+ succeeded. */
+
+static bool
+try_source_highlight (std::string &contents ATTRIBUTE_UNUSED,
+ enum language lang ATTRIBUTE_UNUSED,
+ const std::string &fullname ATTRIBUTE_UNUSED)
+{
+#ifdef HAVE_SOURCE_HIGHLIGHT
+ if (!use_gnu_source_highlight)
+ return false;
+
+ const char *lang_name = get_language_name (lang);
+ if (lang_name == nullptr)
+ return false;
+
+ /* The global source highlight object, or null if one was
+ never constructed. This is stored here rather than in
+ the class so that we don't need to include anything or do
+ conditional compilation in source-cache.h. */
+ static srchilite::SourceHighlight *highlighter;
+
+ bool styled = false;
+ try
+ {
+ if (highlighter == nullptr)
+ {
+ highlighter = new srchilite::SourceHighlight ("esc.outlang");
+ highlighter->setStyleFile ("esc.style");
+ }
+
+ std::istringstream input (contents);
+ std::ostringstream output;
+ highlighter->highlight (input, output, lang_name, fullname);
+ contents = std::move (output).str();
+ styled = true;
+ }
+ catch (...)
+ {
+ /* Source Highlight will throw an exception if
+ highlighting fails. One possible reason it can fail
+ is if the language is unknown -- which matters to gdb
+ because Rust support wasn't added until after 3.1.8.
+ Ignore exceptions here. */
+ }
+
+ return styled;
+#else
+ return false;
+#endif /* HAVE_SOURCE_HIGHLIGHT */
+}
+
/* See source-cache.h. */

bool
@@ -230,44 +283,10 @@ source_cache::ensure (struct symtab *s)

if (source_styling && gdb_stdout->can_emit_style_escape ())
{
-#ifdef HAVE_SOURCE_HIGHLIGHT
- bool already_styled = false;
- const char *lang_name = get_language_name (s->language ());
- if (lang_name != nullptr && use_gnu_source_highlight)
- {
- /* The global source highlight object, or null if one was
- never constructed. This is stored here rather than in
- the class so that we don't need to include anything or do
- conditional compilation in source-cache.h. */
- static srchilite::SourceHighlight *highlighter;
-
- try
- {
- if (highlighter == nullptr)
- {
- highlighter = new srchilite::SourceHighlight ("esc.outlang");
- highlighter->setStyleFile ("esc.style");
- }
-
- std::istringstream input (contents);
- std::ostringstream output;
- highlighter->highlight (input, output, lang_name, fullname);
- contents = std::move (output).str ();
- already_styled = true;
- }
- catch (...)
- {
- /* Source Highlight will throw an exception if
- highlighting fails. One possible reason it can fail
- is if the language is unknown -- which matters to gdb
- because Rust support wasn't added until after 3.1.8.
- Ignore exceptions here and fall back to
- un-highlighted text. */
- }
- }
+ bool already_styled
+ = try_source_highlight (contents, s->language (), fullname);

if (!already_styled)
-#endif /* HAVE_SOURCE_HIGHLIGHT */
{
gdb::optional<std::string> ext_contents;
ext_contents = ext_lang_colorize (fullname, contents);
--
2.35.3