From 8533d7b87f0a54e4c70094c35b5ebd75ed6f0ff8 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Fri, 11 Oct 2013 15:18:37 +0900
Subject: [PATCH] initial parser commit

---
 include/picrin.h |   2 +
 src/parse.y      | 106 +++++++++++++++++++++++++++++++++++++++++++++++
 src/scan.l       |  25 +++++++++++
 3 files changed, 133 insertions(+)
 create mode 100644 src/parse.y
 create mode 100644 src/scan.l

diff --git a/include/picrin.h b/include/picrin.h
index f8346e4e..b5c6fece 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -21,6 +21,8 @@ pic_value pic_cdr(pic_state *, pic_value);
 
 pic_value pic_intern_cstr(pic_state *, const char *);
 
+pic_value pic_parse(pic_state *, const char *);
+
 void pic_debug(pic_state *, pic_value);
 
 #endif
diff --git a/src/parse.y b/src/parse.y
new file mode 100644
index 00000000..37bb0ded
--- /dev/null
+++ b/src/parse.y
@@ -0,0 +1,106 @@
+%{
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "picrin.h"
+
+struct parser_control {
+  pic_state *pic;
+  pic_value value;
+};
+
+#define YYDEBUG 1
+
+%}
+
+%parse-param {struct parser_control *p}
+%lex-param {struct parser_control *p}
+
+%union {
+  pic_value datum;
+}
+
+%token tLPAREN tRPAREN tDOT
+%token <datum> tSYMBOL
+
+%type <datum> datum simple_datum symbol compound_datum
+%type <datum> list list_tail
+
+%%
+
+program
+	:
+	{
+	  p->value = pic_nil_value(p->pic);
+	}
+	| datum
+	{
+	  p->value = $1;
+	}
+;
+
+datum
+	: simple_datum
+	| compound_datum
+;
+
+simple_datum
+	: symbol
+;
+
+symbol
+	: tSYMBOL
+	{
+	  $$ = $1;
+	}
+;
+
+compound_datum
+	: list
+;
+
+list
+	: tLPAREN list_tail
+	{
+	  $$ = $2;
+	}
+;
+
+list_tail
+	: tRPAREN
+	{
+	  $$ = pic_nil_value();
+	}
+	| datum tDOT datum tRPAREN
+	{
+	  $$ = pic_cons(p->pic, $1, $3);
+	}
+	| datum list_tail
+	{
+	  $$ = pic_cons(p->pic, $1, $2);
+	}
+;
+
+%%
+
+int
+yyerror(struct parser_control *p, const char *msg)
+{
+  pic_debug(p->pic, yylval.datum);
+  puts(msg);
+  abort();
+}
+
+pic_value
+pic_parse(pic_state *pic, const char *str)
+{
+  struct parser_control p;
+
+  p.pic = pic;
+
+  yy_scan_string(str);
+  yyparse(&p);
+  yylex_destroy();
+
+  return p.value;
+}
diff --git a/src/scan.l b/src/scan.l
new file mode 100644
index 00000000..7a11d825
--- /dev/null
+++ b/src/scan.l
@@ -0,0 +1,25 @@
+%{
+#include "picrin.h"
+#include "y.tab.h"
+
+struct parser_control {
+  pic_state *pic;
+  pic_value value;
+};
+
+#define YY_DECL int yylex (struct parser_control *p)
+%}
+
+%%
+
+"("	return tLPAREN;
+")"	return tRPAREN;
+[a-z]+	{ yylval.datum = pic_intern_cstr(p->pic, yytext); return tSYMBOL; }
+
+%%
+
+int
+yywrap()
+{
+  return 1;
+}