From ffda3e942f7a41a9ac348cfe60ae27e211545ba3 Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@mutantstargoat.com>
Date: Sun, 9 Oct 2016 12:16:14 +0300
Subject: [PATCH] started the parser

---
 src/mparser.cc |  191 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/mparser.h  |    8 +++
 2 files changed, 199 insertions(+)
 create mode 100644 src/mparser.cc
 create mode 100644 src/mparser.h

diff --git a/src/mparser.cc b/src/mparser.cc
new file mode 100644
index 0000000..b39df1a
--- /dev/null
+++ b/src/mparser.cc
@@ -0,0 +1,191 @@
+#include <vector>
+#include "mparser.h"
+#include "machine.h"
+
+enum ASTNodeType {
+	AST_MACHINE,
+	AST_GEAR,
+	AST_STATEMENT,
+	AST_IDENT,
+	AST_NUMBER,
+	AST_VECTOR,
+	AST_FCALL
+};
+
+struct ASTNode {
+	std::vector<ASTNode*> children;
+};
+
+struct ParserState {
+	FILE *fp;
+	const char *fname;
+	Machine *mcn;
+
+	int nextc;
+	int savedc;
+
+	bool error;
+};
+
+static bool machine(ParserState *ps);
+static bool expect(ParserState *ps, char c);
+static bool expect_alpha(ParserState *ps);
+static bool expect_digit(ParserState *ps);
+static bool expect_alnum(ParserState *ps);
+static bool match_str(ParserState *ps, const char *str);
+static bool match_char(ParserState *ps, char c);
+static bool mstatement(ParserState *ps);
+static bool ident(ParserState *ps, std::string *s);
+static bool gear(ParserState *ps);
+static bool expression(ParserState *ps);
+
+static bool nextchar(ParserState *ps);
+static void putback(ParserState *ps, char c);
+
+bool parse_machine(Machine *mcn, const char *fname)
+{
+	FILE *fp = fopen(fname, "rb");
+	if(!fp) return false;
+
+	ParserState pstate;
+	pstate.fname = fname;
+	pstate.fp = fp;
+	pstate.mcn = mcn;
+	pstate.savedc = -1;
+	pstate.nextc = fgetc(fp);	// prime the parser
+	pstate.error = false;
+
+	bool res = machine(&pstate);
+	fclose(fp);
+	return res;
+}
+
+static bool machine(ParserState *ps)
+{
+	matchstr(ps, "machine");
+	expect(ps, '{');
+
+	while(mstatement(ps));
+
+	expect(ps, '}');
+	return true;
+}
+
+static bool expect(ParserState *ps, int c)
+{
+	if(c != ps->nextc) {
+		ps->error = true;
+		return false;
+	}
+	nextchar(ps);
+	return true;
+}
+
+static bool expect_alpha(ParserState *ps)
+{
+	if(!isalpha(ps->nextc)) {
+		ps->error = true;
+		return false;
+	}
+	nextchar(ps);
+	return true;
+}
+
+static bool expect_digit(ParserState *ps)
+{
+	if(!isdigit(ps->nextc)) {
+		ps->error = true;
+		return false;
+	}
+	nextchar(ps);
+	return true;
+}
+
+static bool expect_alnum(ParserState *ps)
+{
+	if(!isalnum(ps->nextc)) {
+		ps->error = true;
+		return false;
+	}
+	nextchar(ps);
+	return true;
+}
+
+static bool match_str(ParserState *ps, const char *str)
+{
+	while(*str && match_char(ps, *str++));
+	return !feof(ps->fp);
+}
+
+static bool match_char(ParserState *ps, int c)
+{
+	if(ps->nextc != c) {
+		return false;
+	}
+	nextchar(ps);
+	return true;
+}
+
+static bool expression(ParserState *ps);
+
+#define CHECK(x) if(!(x)) return false
+
+static bool mstatement(ParserState *ps)
+{
+	std::string id;
+
+	CHECK(ident(ps, &id));
+	if(id == "gear") {
+		gear(ps);
+	} else {
+		expect(ps, '=');
+		expression(ps);
+	}
+}
+
+static bool expression(ParserState *ps)
+{
+}
+
+static bool ident(ParserState *ps, std::string *s)
+{
+	CHECK(expect_alpha(ps));
+	while(isalnum(ps->nextc) || ps->nextc == '_') {
+		s->append((char)ps->nextc);
+		CHECK(nextchar(ps));
+	}
+	return true;
+}
+
+static bool skip_line(FILE *fp)
+{
+	int c;
+	while((c = fgetc(fp)) != -1 && c != '\n');
+	return c != -1;
+}
+
+static bool nextchar(ParserState *ps)
+{
+	if(ps->savedc != -1) {
+		ps->nextc = ps->savedc;
+		ps->savedc = -1;
+		return true;
+	}
+
+	while((ps->nextc = fgetc(ps->fp)) != -1) {
+		if(ps->nextc == '#') {
+			CHECK(skip_line(ps->fp));
+		}
+		if(!isspace(ps->nextc)) {
+			break;
+		}
+	}
+
+	return ps->nextc != -1;
+}
+
+static void putback(ParserState *ps, char c)
+{
+	ps->savedc = ps->nextc;
+	ps->nextc = c;
+}
diff --git a/src/mparser.h b/src/mparser.h
new file mode 100644
index 0000000..7fa1b6f
--- /dev/null
+++ b/src/mparser.h
@@ -0,0 +1,8 @@
+#ifndef MPARSER_H_
+#define MPARSER_H_
+
+#include <stdio.h>
+
+int parse_machine(Machine *mcn, const char *fname);
+
+#endif	/* MPARSER_H_ */
-- 
1.7.10.4