From 036a5311cbc86dbc5a8f859778d52d588915e4e2 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Thu, 4 Jan 2018 02:23:40 -0800
Subject: [PATCH] altos/scheme: add make-string builtin

Allocate a blank string.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 src/scheme/ao_scheme.h           |  5 ++++-
 src/scheme/ao_scheme_builtin.c   | 30 +++++++++++++++++++++----
 src/scheme/ao_scheme_builtin.txt |  1 +
 src/scheme/ao_scheme_string.c    | 38 ++++++++++++++++++++++++++++----
 4 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/src/scheme/ao_scheme.h b/src/scheme/ao_scheme.h
index 34fb2e88..68803462 100644
--- a/src/scheme/ao_scheme.h
+++ b/src/scheme/ao_scheme.h
@@ -710,7 +710,10 @@ struct ao_scheme_string *
 ao_scheme_string_copy(struct ao_scheme_string *a);
 
 struct ao_scheme_string *
-ao_scheme_string_make(char *a);
+ao_scheme_string_new(char *a);
+
+struct ao_scheme_string *
+ao_scheme_make_string(int32_t len, char fill);
 
 struct ao_scheme_string *
 ao_scheme_atom_to_string(struct ao_scheme_atom *a);
diff --git a/src/scheme/ao_scheme_builtin.c b/src/scheme/ao_scheme_builtin.c
index 0da68778..0b84a89a 100644
--- a/src/scheme/ao_scheme_builtin.c
+++ b/src/scheme/ao_scheme_builtin.c
@@ -762,17 +762,39 @@ ao_scheme_do_string_set(struct ao_scheme_cons *cons)
 	val = ao_scheme_arg_int(_ao_scheme_atom_string2dset21, cons, 2);
 	if (ao_scheme_exception)
 		return AO_SCHEME_NIL;
+	if (!val)
+		goto fail;
 	while (*string && ref) {
 		++string;
 		--ref;
 	}
 	if (!*string)
-		return ao_scheme_error(AO_SCHEME_INVALID, "%v: string %v ref %v invalid",
-				       _ao_scheme_atom_string2dset21,
-				       ao_scheme_arg(cons, 0),
-				       ao_scheme_arg(cons, 1));
+		goto fail;
 	*string = val;
 	return ao_scheme_int_poly(*string);
+fail:
+	return ao_scheme_error(AO_SCHEME_INVALID, "%v: %v[%v] = %v invalid",
+			       _ao_scheme_atom_string2dset21,
+			       ao_scheme_arg(cons, 0),
+			       ao_scheme_arg(cons, 1),
+			       ao_scheme_arg(cons, 2));
+}
+
+ao_poly
+ao_scheme_do_make_string(struct ao_scheme_cons *cons)
+{
+	int32_t	len;
+	char	fill;
+
+	if (!ao_scheme_check_argc(_ao_scheme_atom_make2dstring, cons, 1, 2))
+		return AO_SCHEME_NIL;
+	len = ao_scheme_arg_int(_ao_scheme_atom_make2dstring, cons, 0);
+	if (ao_scheme_exception)
+		return AO_SCHEME_NIL;
+	fill = ao_scheme_opt_arg_int(_ao_scheme_atom_make2dstring, cons, 1, ' ');
+	if (ao_scheme_exception)
+		return AO_SCHEME_NIL;
+	return ao_scheme_string_poly(ao_scheme_make_string(len, fill));
 }
 
 ao_poly
diff --git a/src/scheme/ao_scheme_builtin.txt b/src/scheme/ao_scheme_builtin.txt
index bdadbd6a..4739f121 100644
--- a/src/scheme/ao_scheme_builtin.txt
+++ b/src/scheme/ao_scheme_builtin.txt
@@ -63,6 +63,7 @@ all	f_lambda	string_ref	string-ref
 all	f_lambda	string_set	string-set!
 all	f_lambda	string_copy	string-copy
 all	f_lambda	string_length	string-length
+all	f_lambda	make_string	make-string
 all	f_lambda	procedurep	procedure?
 all	lambda		apply
 all	f_lambda	read_char	read-char
diff --git a/src/scheme/ao_scheme_string.c b/src/scheme/ao_scheme_string.c
index dfc74966..2c636d7a 100644
--- a/src/scheme/ao_scheme_string.c
+++ b/src/scheme/ao_scheme_string.c
@@ -51,6 +51,7 @@ ao_scheme_string_alloc(int len)
 	if (!s)
 		return NULL;
 	s->type = AO_SCHEME_STRING;
+	s->val[len] = '\0';
 	return s;
 }
 
@@ -70,7 +71,19 @@ ao_scheme_string_copy(struct ao_scheme_string *a)
 }
 
 struct ao_scheme_string *
-ao_scheme_string_make(char *a)
+ao_scheme_make_string(int32_t len, char fill)
+{
+	struct ao_scheme_string	*r;
+
+	r = ao_scheme_string_alloc(len);
+	if (!r)
+		return NULL;
+	memset(r->val, fill, len);
+	return r;
+}
+
+struct ao_scheme_string *
+ao_scheme_string_new(char *a)
 {
 	struct ao_scheme_string	*r;
 
@@ -138,7 +151,6 @@ ao_scheme_string_pack(struct ao_scheme_cons *cons)
 			return ao_scheme_error(AO_SCHEME_INVALID, "non-int passed to pack");
 		cons = ao_scheme_cons_cdr(cons);
 	}
-	*rval++ = 0;
 	return ao_scheme_string_poly(r);
 }
 
@@ -183,14 +195,32 @@ ao_scheme_string_write(ao_poly p, bool write)
 		putchar('"');
 		while ((c = *sval++)) {
 			switch (c) {
+			case '\a':
+				printf("\\a");
+				break;
+			case '\b':
+				printf("\\b");
+				break;
+			case '\t':
+				printf ("\\t");
+				break;
 			case '\n':
 				printf ("\\n");
 				break;
 			case '\r':
 				printf ("\\r");
 				break;
-			case '\t':
-				printf ("\\t");
+			case '\f':
+				printf("\\f");
+				break;
+			case '\v':
+				printf("\\v");
+				break;
+			case '\"':
+				printf("\\\"");
+				break;
+			case '\\':
+				printf("\\\\");
 				break;
 			default:
 				if (c < ' ')
-- 
2.30.2