Basic structure of ftepp

ftepp.c

@@ -24,10 +24,44 @@
 #include "lexer.h"
 
 typedef struct {
-	lex_file *lex;
+	bool on;
+	bool was_on;
+	bool had_else;
+} ppcondition;
+
+typedef struct {
+	lex_file    *lex;
+	int          token;
+	bool         newline;
+	unsigned int errors;
+
+	ppcondition *conditions;
 } ftepp_t;
 
 #define ftepp_tokval(f) ((f)->lex->tok.value)
+#define ftepp_ctx(f)    ((f)->lex->tok.ctx)
+
+static void ftepp_errorat(ftepp_t *ftepp, lex_ctx ctx, const char *fmt, ...)
+{
+	va_list ap;
+
+	ftepp->errors++;
+
+	va_start(ap, fmt);
+    con_vprintmsg(LVL_ERROR, ctx.file, ctx.line, "error", fmt, ap);
+	va_end(ap);
+}
+
+static void ftepp_error(ftepp_t *ftepp, const char *fmt, ...)
+{
+	va_list ap;
+
+	ftepp->errors++;
+
+	va_start(ap, fmt);
+    con_vprintmsg(LVL_ERROR, ftepp->lex->tok.ctx.file, ftepp->lex->tok.ctx.line, "error", fmt, ap);
+	va_end(ap);
+}
 
 ftepp_t* ftepp_init()
 {
@@ -39,23 +73,192 @@ ftepp_t* ftepp_init()
 	return ftepp;
 }
 
+static inline int ftepp_next(ftepp_t *ftepp)
+{
+	return (ftepp->token = lex_do(ftepp->lex));
+}
+
+/* Important: this does not skip newlines! */
+static bool ftepp_skipspace(ftepp_t *ftepp)
+{
+	while (ftepp_next(ftepp) == TOKEN_WHITE) {}
+	return (ftepp->token < TOKEN_EOF);
+}
+
+static bool ftepp_if(ftepp_t *ftepp, ppcondition *cond)
+{
+	ftepp_error(ftepp, "TODO: #if");
+	return false;
+}
+
+static bool ftepp_ifdef(ftepp_t *ftepp, ppcondition *cond)
+{
+	ftepp_error(ftepp, "TODO: #ifdef");
+	return false;
+}
+
+static bool ftepp_define(ftepp_t *ftepp)
+{
+	ftepp_error(ftepp, "TODO: #define");
+	return false;
+}
+
+static bool ftepp_else_allowed(ftepp_t *ftepp)
+{
+	if (!vec_size(ftepp->conditions)) {
+		ftepp_error(ftepp, "#else without #if");
+		return false;
+	}
+	if (vec_last(ftepp->conditions).had_else) {
+		ftepp_error(ftepp, "multiple #else for a single #if");
+		return false;
+	}
+	return true;
+}
+
+static bool ftepp_hash(ftepp_t *ftepp)
+{
+	ppcondition cond;
+	ppcondition *pc;
+
+	lex_ctx ctx = ftepp_ctx(ftepp);
+
+	if (!ftepp_skipspace(ftepp))
+		return false;
+
+	switch (ftepp->token) {
+		case TOKEN_IDENT:
+			if (!strcmp(ftepp_tokval(ftepp), "define")) {
+				return ftepp_define(ftepp);
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "ifdef")) {
+				if (!ftepp_ifdef(ftepp, &cond))
+					return false;
+				vec_push(ftepp->conditions, cond);
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "ifndef")) {
+				if (!ftepp_ifdef(ftepp, &cond))
+					return false;
+				cond.on = !cond.on;
+				vec_push(ftepp->conditions, cond);
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "elifdef")) {
+				if (!ftepp_else_allowed(ftepp))
+					return false;
+				if (!ftepp_ifdef(ftepp, &cond))
+					return false;
+				pc = &vec_last(ftepp->conditions);
+				pc->on     = !pc->was_on && cond.on;
+				pc->was_on = pc->was_on || pc->on;
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "elifndef")) {
+				if (!ftepp_else_allowed(ftepp))
+					return false;
+				if (!ftepp_ifdef(ftepp, &cond))
+					return false;
+				cond.on = !cond.on;
+				pc = &vec_last(ftepp->conditions);
+				pc->on     = !pc->was_on && cond.on;
+				pc->was_on = pc->was_on || pc->on;
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "elif")) {
+				if (!ftepp_else_allowed(ftepp))
+					return false;
+				if (!ftepp_if(ftepp, &cond))
+					return false;
+				pc = &vec_last(ftepp->conditions);
+				pc->on     = !pc->was_on && cond.on;
+				pc->was_on = pc->was_on  || pc->on;
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "if")) {
+				if (!ftepp_if(ftepp, &cond))
+					return false;
+				vec_push(ftepp->conditions, cond);
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "else")) {
+				if (!ftepp_else_allowed(ftepp))
+					return false;
+				pc = &vec_last(ftepp->conditions);
+				pc->on = !pc->was_on;
+				pc->had_else = true;
+				return true;
+			}
+			else if (!strcmp(ftepp_tokval(ftepp), "endif")) {
+				if (!vec_size(ftepp->conditions)) {
+					ftepp_error(ftepp, "#endif without #if");
+					return false;
+				}
+				vec_pop(ftepp->conditions);
+				break;
+			}
+			else {
+				ftepp_error(ftepp, "unrecognized preprocessor directive: `%s`", ftepp_tokval(ftepp));
+				return false;
+			}
+			break;
+		case TOKEN_KEYWORD:
+			if (!strcmp(ftepp_tokval(ftepp), "if")) {
+				if (!ftepp_if(ftepp, &cond))
+					return false;
+				vec_push(ftepp->conditions, cond);
+				return true;
+			}
+		/* fall through */
+		default:
+			ftepp_error(ftepp, "unexpected preprocessor token: `%s`", ftepp_tokval(ftepp));
+			return false;
+		case TOKEN_EOL:
+			ftepp_errorat(ftepp, ctx, "empty preprocessor directive");
+			return false;
+		case TOKEN_EOF:
+			ftepp_error(ftepp, "missing newline at end of file", ftepp_tokval(ftepp));
+			return false;
+	}
+	return true;
+}
+
 static bool ftepp_preprocess(ftepp_t *ftepp)
 {
-	int token;
+	bool newline = true;
 
 	ftepp->lex->flags.preprocessing = true;
 
-	for (token = lex_do(ftepp->lex); token < TOKEN_EOF; token = lex_do(ftepp->lex))
+	do
 	{
-		switch (token) {
-			case TOKEN_EOL: printf("\n"); break;
+		ftepp_next(ftepp);
+
+		if (ftepp->token >= TOKEN_EOF)
+			break;
+
+		ftepp->newline = newline;
+		newline = false;
+
+		switch (ftepp->token) {
+			case '#':
+				if (!ftepp->newline) {
+					printf("%s", ftepp_tokval(ftepp));
+					break;
+				}
+				if (!ftepp_hash(ftepp))
+					return false;
+				break;
+			case TOKEN_EOL:
+				newline = true;
+				printf("\n");
+				break;
 			default:
 				printf("%s", ftepp_tokval(ftepp));
 				break;
 		}
-	}
+	} while (!ftepp->errors && ftepp->token < TOKEN_EOF);
 
-	return (token == TOKEN_EOF);
+	return (ftepp->token == TOKEN_EOF);
 }
 
 bool ftepp_preprocess_file(const char *filename)