Substitute defines with their strings.

Before allocating space for a token, the lexer will first check to see
if that token is a defined name. If it is, it will allocate space for
the defined string instead.

A test file is included in programs/tinyvm/preprocessor to demonstrate
the behavior. When functioning, the program will print the fibonacci
sequence.

include/tvm/tvm_lexer.h

@@ -4,6 +4,8 @@
 #define MAX_ARGS 2
 #define MAX_TOKENS 4
 
+#include "tvm_tree.h"
+
 typedef struct tvm_lexer_s
 {
 	char **source_lines;
@@ -14,6 +16,6 @@ tvm_lexer_t *lexer_create();
 void lexer_destroy(tvm_lexer_t *l);
 
 /* Tokenize the character array "source" into lines and tokens */
-void lex(tvm_lexer_t *lexer, char *source);
+void lex(tvm_lexer_t *lexer, char *source, tvm_tree_t **node);
 
 #endif

libtvm/tvm_lexer.c

@@ -26,7 +26,7 @@ void lexer_destroy(tvm_lexer_t *lexer)
 	free(lexer);
 }
 
-void lex(tvm_lexer_t *lexer, char *source)
+void lex(tvm_lexer_t *lexer, char *source, tvm_tree_t **node)
 {
 	int i, j;
 	char *pToken, *pLine = strtok(source, "\n");
@@ -60,8 +60,12 @@ void lex(tvm_lexer_t *lexer, char *source)
 
 		for(j = 0; (pToken && j < MAX_TOKENS); j++)
 		{
-			lexer->tokens[i][j] = (char *)calloc(1, (strlen(pToken) + 1));
-			strcpy(lexer->tokens[i][j], pToken);
+			/* Check if this token is a define. */
+			char *token = (char *)tvm_tree_find(*node, pToken);
+			if(!token) token = pToken;
+
+			lexer->tokens[i][j] = (char *)calloc(1, (strlen(token) + 1));
+			strcpy(lexer->tokens[i][j], token);
 
 			pToken = strtok(NULL, " \t,");
 		}

libtvm/tvm_program.c

@@ -58,7 +58,7 @@ pi_interpret:
 	while(tvm_preprocess(source, &source_length, &p->defines));
 
 	tvm_lexer_t *lexer_ctx = lexer_create();
-	lex(lexer_ctx, source);
+	lex(lexer_ctx, source, &p->defines);
 	free(source);
 
 	if(parse_labels(p, (const char ***)lexer_ctx->tokens) != 0) return 1;

programs/tinyvm/preprocessor/define.vm

@@ -0,0 +1,20 @@
+%define ONE 1
+%define ZERO 0
+
+start:
+	mov eax, ONE
+	mov ebx, ZERO
+
+loop:	add eax, ebx
+	add ebx, eax
+
+	prn eax
+	prn ebx
+
+	cmp eax, ZERO
+	jl end
+
+	cmp ebx, ZERO
+	jg loop
+
+end: