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glcpp: Rewrite line-continuation support to act globally. 

Previously, we were only supporting line-continuation backslash characters
within lines of pre-processor directives, (as per the specification). With
OpenGL 4.2 and GLES3, line continuations are now supported anywhere within a
shader.

While changing this, also fix a bug where the preprocessor was ignoring
line continuation characters when a line ended in multiple backslash
characters.

The new code is also more efficient than the old. Previously, we would
perform a ralloc copy at each newline. We now perform copies only at each
occurrence of a line-continuation.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Carl Worth 2012-11-29 14:49:46 -08:00
parent 60a11e295b
commit 962a1c07b4
1 changed files with 41 additions and 64 deletions
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105
src/glsl/glcpp/pp.c
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@ -70,82 +70,59 @@ glcpp_warning (YYLTYPE *locp, glcpp_parser_t *parser, const char *fmt, ...)
&parser->info_log_length, "\n");
}
/* Searches backwards for '^ *#' from a given starting point. */
static int
in_directive(const char *shader, const char *ptr)
{
assert(ptr >= shader);
/* Search backwards for '#'. If we find a \n first, it doesn't count */
for (; ptr >= shader && *ptr != '#'; ptr--) {
if (*ptr == '\n')
return 0;
}
if (ptr >= shader) {
/* Found '#'...look for spaces preceded by a newline */
for (ptr--; ptr >= shader && isblank(*ptr); ptr--);
// FIXME: I don't think the '\n' case can happen
if (ptr < shader || *ptr == '\n')
return 1;
}
return 0;
}
/* Remove any line continuation characters in preprocessing directives.
* However, ignore any in GLSL code, as "There is no line continuation
* character" (1.30 page 9) in GLSL.
/* Remove any line continuation characters in the shader, (whether in
* preprocessing directives or in GLSL code).
*/
static char *
remove_line_continuations(glcpp_parser_t *ctx, const char *shader)
{
int in_continued_line = 0;
int extra_newlines = 0;
char *clean = ralloc_strdup(ctx, "");
const char *search_start = shader;
const char *newline;
while ((newline = strchr(search_start, '\n')) != NULL) {
const char *backslash = NULL;
const char *backslash, *newline;
int collapsed_newlines = 0;
/* # of characters preceding the newline. */
int n = newline - shader;
while (true) {
backslash = strchr(shader, '\\');
/* Find the preceding '\', if it exists */
if (n >= 1 && newline[-1] == '\\')
backslash = newline - 1;
else if (n >= 2 && newline[-1] == '\r' && newline[-2] == '\\')
backslash = newline - 2;
/* Double backslashes don't count (the backslash is escaped) */
if (backslash != NULL && backslash[-1] == '\\') {
backslash = NULL;
}
if (backslash != NULL) {
/* We found a line continuation, but do we care? */
if (!in_continued_line) {
if (in_directive(shader, backslash)) {
in_continued_line = 1;
extra_newlines = 0;
}
}
if (in_continued_line) {
/* Copy everything before the \ */
ralloc_strncat(&clean, shader, backslash - shader);
/* If we have previously collapsed any line-continuations,
* then we want to insert additional newlines at the next
* occurrence of a newline character to avoid changing any
* line numbers.
*/
if (collapsed_newlines) {
newline = strchr(shader, '\n');
if (newline &&
(backslash == NULL || newline < backslash))
{
ralloc_strncat(&clean, shader,
newline - shader + 1);
while (collapsed_newlines--)
ralloc_strcat(&clean, "\n");
shader = newline + 1;
extra_newlines++;
}
} else if (in_continued_line) {
/* Copy everything up to and including the \n */
ralloc_strncat(&clean, shader, newline - shader + 1);
shader = newline + 1;
/* Output extra newlines to make line numbers match */
for (; extra_newlines > 0; extra_newlines--)
ralloc_strcat(&clean, "\n");
in_continued_line = 0;
}
search_start = newline + 1;
if (backslash == NULL)
break;
/* At each line continuation, (backslash followed by a
* newline), copy all preceding text to the output, then
* advance the shader pointer to the character after the
* newline.
*/
if (backslash[1] == '\n' ||
(backslash[1] == '\r' && backslash[2] == '\n'))
{
collapsed_newlines++;
ralloc_strncat(&clean, shader, backslash - shader);
if (backslash[1] == '\n')
shader = backslash + 2;
else
shader = backslash + 3;
}
}
ralloc_strcat(&clean, shader);
return clean;
}