--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lwbasic/parser.c	Thu Feb 03 21:19:11 2011 -0700
@@ -0,0 +1,212 @@
+/*
+compiler.c
+
+Copyright © 2011 William Astle
+
+This file is part of LWTOOLS.
+
+LWTOOLS is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+more details.
+
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+This is the actual compiler bit; it drives the parser and code generation
+*/
+
+#include <stdio.h>
+
+#include <lw_alloc.h>
+#include <lw_string.h>
+
+#include "lwbasic.h"
+
+/* parse a type; the next token will be acquired as a result */
+/* the token advancement is to provide consistency */
+static int parse_type(cstate *state)
+{
+	int pt = -1;
+	
+	switch (state -> lexer_token)
+	{
+	case token_kw_integer:
+		pt = 1;
+		break;
+
+	default:
+		lwb_error("Invalid type specification");
+	}
+	lexer(state);
+	/* look for "unsigned" modifier for integer types */
+	return pt;
+}
+
+
+/* issub means RETURNS is not allowed; !issub means RETURNS is required */
+static void parse_subfunc(cstate *state, int issub)
+{
+	int pt;
+	char *subname;
+	int vis = 0;
+			
+	lexer(state);
+	if (state -> lexer_token != token_identifier)
+	{
+		lwb_error("Invalid sub name '%s'", state -> lexer_token_string);
+	}
+	
+	subname = lw_strdup(state -> lexer_token_string);
+	
+	lexer(state);
+	if (state -> lexer_token == token_kw_public || state -> lexer_token == token_kw_private)
+	{
+		if (state -> lexer_token == token_kw_public)
+			vis = 1;
+		lexer(state);
+	}
+
+	/* ignore the "PARAMS" keyword if present */
+	if (state -> lexer_token == token_kw_params)
+		lexer(state);
+	
+	if (state -> lexer_token == token_eol || state -> lexer_token == token_kw_returns)
+		goto noparms;
+
+paramagain:
+	if (state -> lexer_token != token_identifier)
+	{
+		lwb_error("Parameter name expected, got %d, %s\n", state -> lexer_token, state -> lexer_token_string);
+	}
+	printf("Got <param> = %s\n", state -> lexer_token_string);
+	lexer(state);
+	
+	if (state -> lexer_token != token_kw_as)
+		lwb_error("Expecting AS\n");
+	lexer(state);
+	
+	pt = parse_type(state);
+	printf("Got <type> = %d\n", pt);
+	
+	if (state -> lexer_token == token_char && state -> lexer_token_string[0] == ',')
+	{
+		lexer(state);
+		goto paramagain;
+	}
+
+noparms:	
+	if (!issub)
+	{
+		int rt;
+		
+		if (state -> lexer_token != token_kw_returns)
+		{
+			lwb_error("FUNCTION must have RETURNS\n");
+		}
+		lexer(state);
+		if (state -> lexer_token == token_identifier)
+		{
+			printf("Return value named: %s\n", state -> lexer_token_string);
+			lexer(state);
+			if (state -> lexer_token != token_kw_as)
+				lwb_error("Execting AS after RETURNS");
+			lexer(state);
+		}
+		rt = parse_type(state);
+		printf("Return type: %d\n", rt);
+	}
+	else
+	{
+		if (state -> lexer_token == token_kw_returns)
+		{
+			lwb_error("SUB cannot specify RETURNS\n");
+		}
+	}
+
+	
+	if (state -> lexer_token != token_eol)
+	{
+		lwb_error("EOL expected; found %d, %s\n", state -> lexer_token, state -> lexer_token_string);
+	}
+
+	
+	printf("Sub/Func %s, vis %s\n", subname, vis ? "public" : "private");
+
+	state -> currentsub = subname;
+
+	/* consume EOL */
+	lexer(state);
+	
+	/* variable declarations */
+	/* parse_decls(state); */
+	
+	/* output function/sub prolog */
+	emit_prolog(state, vis, 0);
+	
+	/* parse statement block  */
+	/* parse_statemetns(state); */
+	
+	if (issub)
+	{
+		if (state -> lexer_token != token_kw_endsub)
+		{
+			lwb_error("Expecting ENDSUB, got %d (%s)\n", state -> lexer_token, state -> lexer_token_string);
+		}
+	}
+	else
+	{
+		if (state -> lexer_token != token_kw_endfunction)
+		{
+			lwb_error("Expecting ENDFUNCTION, got %d (%s)\n", state -> lexer_token, state -> lexer_token_string);
+		}
+	}
+	/* output function/sub epilog */
+	emit_epilog(state, 0);
+	
+	lw_free(state -> currentsub);
+	state -> currentsub = NULL;
+	
+}
+
+void parser(cstate *state)
+{
+	state -> lexer_curchar = -1;
+	
+	/* now look for a global declaration */
+	for (;;)
+	{
+		state -> parser_state = parser_state_global;
+		lexer(state);
+		switch (state -> lexer_token)
+		{
+		case token_kw_function:
+			printf("Function\n");
+			parse_subfunc(state, 0);
+			break;
+			
+		case token_kw_sub:
+			printf("Sub\n");
+			parse_subfunc(state, 1);
+			break;
+
+		/* blank lines are allowed */
+		case token_eol:
+			continue;
+		
+		/* EOF is allowed - end of parsing */
+		case token_eof:
+			return;
+
+		default:
+			lwb_error("Invalid token %d, %s in global state\n", state -> lexer_token, state -> lexer_token_string);
+		}
+	}	
+}