Added BLC parsing/printing

1 files changed, 43 insertions, 9 deletions

diff --git a/src/parse.c b/src/parse.c
index 33ca556..0b9fd82 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -1,13 +1,11 @@
 // Copyright (c) 2023, Marvin Borner <dev@marvinborner.de>
-// Just for testing purposes
-// -> parses custom bruijn syntax
 
 #include <stdio.h>
 
 #include <parse.h>
 #include <term.h>
 
-static struct term *rec(const char **term)
+static struct term *rec_bruijn(const char **term)
 {
 	struct term *res = 0;
 	if (!**term) {
@@ -15,12 +13,12 @@ static struct term *rec(const char **term)
 	} else if (**term == '[') {
 		(*term)++;
 		res = new_term(ABS);
-		res->u.abs.term = rec(term);
+		res->u.abs.term = rec_bruijn(term);
 	} else if (**term == '(') {
 		(*term)++;
 		res = new_term(APP);
-		res->u.app.lhs = rec(term);
-		res->u.app.rhs = rec(term);
+		res->u.app.lhs = rec_bruijn(term);
+		res->u.app.rhs = rec_bruijn(term);
 	} else if (**term >= '0' && **term <= '9') {
 		res = new_term(VAR);
 		res->u.var.name = **term - '0';
@@ -28,14 +26,50 @@ static struct term *rec(const char **term)
 		(*term)++;
 	} else {
 		(*term)++;
-		res = rec(term); // this is quite tolerant..
+		res = rec_bruijn(term); // this is quite tolerant..
 	}
 	return res;
 }
 
-struct term *parse(const char *term)
+static struct term *rec_blc(const char **term)
 {
-	struct term *parsed = rec(&term);
+	struct term *res = 0;
+	if (!**term) {
+		fprintf(stderr, "invalid parsing state!\n");
+	} else if (**term == '0' && *(*term + 1) == '0') {
+		(*term) += 2;
+		res = new_term(ABS);
+		res->u.abs.term = rec_blc(term);
+	} else if (**term == '0' && *(*term + 1) == '1') {
+		(*term) += 2;
+		res = new_term(APP);
+		res->u.app.lhs = rec_blc(term);
+		res->u.app.rhs = rec_blc(term);
+	} else if (**term == '1') {
+		const char *cur = *term;
+		while (**term == '1')
+			(*term)++;
+		res = new_term(VAR);
+		res->u.var.name = *term - cur - 1;
+		res->u.var.type = BRUIJN_INDEX;
+		(*term)++;
+	} else {
+		(*term)++;
+		res = rec_blc(term); // this is quite tolerant..
+	}
+	return res;
+}
+
+struct term *parse_bruijn(const char *term)
+{
+	struct term *parsed = rec_bruijn(&term);
+	to_barendregt(parsed);
+	return parsed;
+}
+
+struct term *parse_blc(const char *term)
+{
+	struct term *parsed = rec_blc(&term);
 	to_barendregt(parsed);
 	return parsed;
 }