From d4b977d0904a1dea37922dac60d3bb37f9769230 Mon Sep 17 00:00:00 2001
From: David Walter Seikel
Date: Thu, 5 Jan 2012 04:47:56 +1000
Subject: Add a simple flex + btyacc stub.

Will be fleshed out soon with LSL grammer.
---
 LuaSL/src/LuaSL_parser.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 LuaSL/src/LuaSL_parser.c

(limited to 'LuaSL/src/LuaSL_parser.c')

diff --git a/LuaSL/src/LuaSL_parser.c b/LuaSL/src/LuaSL_parser.c
new file mode 100644
index 0000000..9e1d3ca
--- /dev/null
+++ b/LuaSL/src/LuaSL_parser.c
@@ -0,0 +1,86 @@
+#include "LuaSL_parser_param.h"
+#include "LuaSL_yaccer.tab.h"
+ 
+ 
+int yyparse(void *param);
+ 
+static int initParserParam(SParserParam* param)
+{
+        int ret = 0;
+ 
+        ret = yylex_init(&param->scanner);
+        param->expression = NULL;
+ 
+        return ret;
+}
+ 
+static int destroyParserParam(SParserParam* param)
+{
+        return yylex_destroy(param->scanner);
+}
+ 
+SExpression *getAST(const char *expr)
+{
+        SParserParam p;
+        YY_BUFFER_STATE state;
+ 
+        if ( initParserParam(&p) )
+        {
+                // couldn't initialize
+                return NULL;
+        }
+ 
+        state = yy_scan_string(expr, p.scanner);
+ 
+        if ( yyparse(&p) )
+        {
+                // error parsing
+                return NULL;
+        }
+ 
+        yy_delete_buffer(state, p.scanner);
+ 
+        destroyParserParam(&p);
+ 
+        return p.expression;
+}
+ 
+int evaluate(SExpression *e)
+{
+        switch(e->type)
+        {
+                case eVALUE:
+                        return e->value;
+                case eMULTIPLY:
+                        return evaluate(e->left) * evaluate(e->right);
+                case ePLUS:
+                        return evaluate(e->left) + evaluate(e->right);
+                default:
+                        // shouldn't be here
+                        return 0;
+        }
+}
+
+int yyerror(const char *msg)
+{
+	fprintf(stderr,"Error:%s\n",msg); return 0;
+}
+
+int main(void)
+{
+        SExpression *e = NULL;
+        char test[]=" 4 + 2*10 + 3*( 5 + 1 )";
+        int result = 0;
+ 
+        e = getAST(test);
+ 
+        result = evaluate(e);
+ 
+        printf("Result of '%s' is %d\n", test, result);
+ 
+        deleteExpression(e);
+ 
+        return 0;
+}
+
+
-- 
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