[PATCH vkd3d 3/4] vkd3d-shader: Implement #else.

[Zebediah Figura]

Signed-off-by: Zebediah Figura 
---
 libs/vkd3d-shader/preproc.h |  4 ++++
 libs/vkd3d-shader/preproc.l |  3 +++
 libs/vkd3d-shader/preproc.y | 25 +++++++++++++++++++++++++
 3 files changed, 32 insertions(+)

diff --git a/libs/vkd3d-shader/preproc.h b/libs/vkd3d-shader/preproc.h
index 224ae5b2..c05e3f6d 100644
--- a/libs/vkd3d-shader/preproc.h
+++ b/libs/vkd3d-shader/preproc.h
@@ -33,6 +33,10 @@ struct preproc_if_state
 {
     /* Are we currently in a "true" block? */
     bool current_true;
+    /* Have we seen a "true" block in this #if..#endif yet? */
+    bool seen_true;
+    /* Have we seen an #else yet? */
+    bool seen_else;
 };

struct preproc_ctx
diff --git a/libs/vkd3d-shader/preproc.l b/libs/vkd3d-shader/preproc.l
index dd2b9c0a..fc3c5fa2 100644
--- a/libs/vkd3d-shader/preproc.l
+++ b/libs/vkd3d-shader/preproc.l
@@ -100,6 +100,8 @@ IDENTIFIER      [A-Za-z_][A-Za-z0-9_]*
         for (p = yytext + 1; strchr(" \t", *p); ++p)
             ;

+        if (!strcmp(p, "else"))
+            return T_ELSE;
         if (!strcmp(p, "endif"))
             return T_ENDIF;
         if (!strcmp(p, "if"))
@@ -190,6 +192,7 @@ int yylex(YYSTYPE *lval, YYLTYPE *lloc, yyscan_t scanner)
         {
             switch (token)
             {
+                case T_ELSE:
                 case T_ENDIF:
                 case T_IF:
                     ctx->current_directive = token;
diff --git a/libs/vkd3d-shader/preproc.y b/libs/vkd3d-shader/preproc.y
index fda04a07..add39735 100644
--- a/libs/vkd3d-shader/preproc.y
+++ b/libs/vkd3d-shader/preproc.y
@@ -105,6 +105,8 @@ static bool preproc_push_if(struct preproc_ctx *ctx, bool condition)
         return false;
     state = &ctx->if_stack[ctx->if_count++];
     state->current_true = condition && preproc_was_writing(ctx);
+    state->seen_true = condition;
+    state->seen_else = false;
     return true;
 }

@@ -161,6 +163,7 @@ static uint32_t preproc_parse_integer(const char *s)

%token T_NEWLINE

+%token T_ELSE "#else"
 %token T_ENDIF "#endif"
 %token T_IF "#if"

@@ -181,6 +184,28 @@ directive
             if (!preproc_push_if(ctx, !!$2))
                 YYABORT;
         }
+    | T_ELSE T_NEWLINE
+        {
+            if (ctx->if_count)
+            {
+                struct preproc_if_state *state = &ctx->if_stack[ctx->if_count - 1];
+
+                if (state->seen_else)
+                {
+                    preproc_warning(ctx, &@$, VKD3D_SHADER_WARNING_PP_INVALID_DIRECTIVE, "Ignoring #else after #else.");
+                }
+                else
+                {
+                    state->current_true = !state->seen_true && preproc_was_writing(ctx);
+                    state->seen_else = true;
+                }
+            }
+            else
+            {
+                preproc_warning(ctx, &@$, VKD3D_SHADER_WARNING_PP_INVALID_DIRECTIVE,
+                        "Ignoring #else without prior #if.");
+            }
+        }
     | T_ENDIF T_NEWLINE
         {
             if (ctx->if_count)