glcpp: Support line continuations within preprocessor directives.

Fixes CorrectPreprocess5.frag.

1 files changed, 79 insertions, 0 deletions

diff --git a/glcpp/pp.c b/glcpp/pp.c
index 5455518..a25b7b7 100644
--- a/glcpp/pp.c
+++ b/glcpp/pp.c
@@ -21,6 +21,8 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <assert.h>
+#include <ctype.h>
 #include "glcpp.h"
 
 void
@@ -56,11 +58,88 @@ glcpp_warning (YYLTYPE *locp, glcpp_parser_t *parser, const char *fmt, ...)
 	parser->info_log = talloc_strdup_append(parser->info_log, "\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.
+ */
+static char *
+remove_line_continuations(glcpp_parser_t *ctx, const char *shader)
+{
+	int in_continued_line = 0;
+	int extra_newlines = 0;
+	char *clean = talloc_strdup(ctx, "");
+	const char *search_start = shader;
+	const char *newline;
+	while ((newline = strchr(search_start, '\n')) != NULL) {
+		const char *backslash = NULL;
+		/* Find the preceding '\', if it exists */
+		if (newline[-1] == '\\') {
+			backslash = newline - 1;
+		} else if (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 \ */
+				clean = talloc_strndup_append(clean, shader, backslash - shader);
+				shader = newline + 1;
+				extra_newlines++;
+			}
+		} else if (in_continued_line) {
+			/* Copy everything up to and including the \n */
+			clean = talloc_strndup_append(clean, shader, newline - shader + 1);
+			shader = newline + 1;
+			/* Output extra newlines to make line numbers match */
+			for (; extra_newlines > 0; extra_newlines--)
+				clean = talloc_strdup_append(clean, "\n");
+			in_continued_line = 0;
+		}
+		search_start = newline + 1;
+	}
+	clean = talloc_strdup_append(clean, shader);
+	return clean;
+}
+
 extern int
 preprocess(void *talloc_ctx, const char **shader, char **info_log)
 {
 	int errors;
 	glcpp_parser_t *parser = glcpp_parser_create ();
+	*shader = remove_line_continuations(parser, *shader);
+
 	glcpp_lex_set_source_string (parser, *shader);
 
 	glcpp_parser_parse (parser);