From a8aa6b2c5e570409d1c87a6bd42d652336f3b1ff Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Fri, 21 Feb 2014 18:24:20 +0900
Subject: [PATCH] add some string utility functions

---
 include/picrin.h |  3 +++
 src/string.c     | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/picrin.h b/include/picrin.h
index 1da8a491..5246acee 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -166,6 +166,9 @@ char *pic_strdup(pic_state *, const char *);
 char *pic_strndup(pic_state *, const char *, size_t);
 pic_str *pic_str_new(pic_state *, const char * /* nullable */, size_t);
 pic_str *pic_str_new_cstr(pic_state *, const char *);
+char pic_str_ref(pic_state *, pic_str *, size_t);
+pic_str *pic_strcat(pic_state *, pic_str *, pic_str *);
+pic_str *pic_substr(pic_state *, pic_str *, size_t, size_t);
 
 pic_value pic_format(pic_state *, const char *, ...);
 pic_value pic_vformat(pic_state *, const char *, va_list);
diff --git a/src/string.c b/src/string.c
index f7437c37..a491e4c8 100644
--- a/src/string.c
+++ b/src/string.c
@@ -32,6 +32,45 @@ pic_str_new_cstr(pic_state *pic, const char *cstr)
   return pic_str_new(pic, cstr, strlen(cstr));
 }
 
+char
+pic_str_ref(pic_state *pic, pic_str *str, size_t n)
+{
+  UNUSED(pic);
+
+  return str->str[n];
+}
+
+pic_str *
+pic_strcat(pic_state *pic, pic_str *a, pic_str *b)
+{
+  size_t len;
+  char *buf;
+
+  len = a->len + b->len;
+  buf = pic_alloc(pic, len + 1);
+
+  memcpy(buf, a->str, a->len);
+  memcpy(buf + a->len, b->str, b->len);
+  buf[len] = '\0';
+
+  return pic_str_new(pic, buf, len);
+}
+
+pic_str *
+pic_substr(pic_state *pic, pic_str *str, size_t s, size_t e)
+{
+  size_t len;
+  char *buf;
+
+  len = e - s;
+  buf = pic_alloc(pic, len + 1);
+
+  memcpy(buf, str->str + s, len);
+  buf[len] = '\0';
+
+  return pic_str_new(pic, buf, len);
+}
+
 pic_value
 pic_vfformat(pic_state *pic, XFILE *file, const char *fmt, va_list ap)
 {