From 545783c1d937b2bed42e0555c9343fa00b8b7a22 Mon Sep 17 00:00:00 2001
From: hgn <hgodden00@gmail.com>
Date: Tue, 5 Dec 2023 15:19:43 +0000
Subject: [PATCH] add support for dynamic vg_str's (tooling)

---
 vg_platform.h | 119 ++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 100 insertions(+), 19 deletions(-)

diff --git a/vg_platform.h b/vg_platform.h
index ef3daed..295f03f 100644
--- a/vg_platform.h
+++ b/vg_platform.h
@@ -44,6 +44,7 @@ struct vg_achievement
 #include <math.h>
 #include <stdio.h>
 #include <errno.h>
+#include <stdlib.h>
 
 enum strncpy_behaviour{
    k_strncpy_always_add_null = 0,
@@ -75,47 +76,121 @@ static u32 vg_strncpy( const char *src, char *dst, u32 len,
 }
 
 typedef struct vg_str vg_str;
+typedef struct vg_str_dynamic vg_str_dynamic;
+
 struct vg_str{
    char *buffer;
-   i32 i, len;
+   i32 i,   /* -1: error condition. otherwise, current cursor position */
+       len; /* -1: dynamically allocated. otherwise, buffer length */
+};
+
+struct vg_str_dynamic {
+   i32 len;
 };
 
+/* 
+ * Returns the current storage size of the string
+ */
+static i32 vg_str_storage( vg_str *str ){
+   if( str->len == -1 ){
+      if( str->buffer ){
+         vg_str_dynamic *arr = (vg_str_dynamic *)str->buffer;
+         return (arr-1)->len;
+      }
+      else return 0;
+   }
+   else return str->len;
+}
+
+/*
+ * Reset string. If len is -1 (dynamically allocated), buffer must be either 
+ * NULL or be acquired from malloc or realloc
+ */
 static void vg_strnull( vg_str *str, char *buffer, i32 len ){
    str->buffer = buffer;
-   str->buffer[0] = '\0';
+   if( buffer )
+      str->buffer[0] = '\0';
+
    str->i = 0;
    str->len = len;
 
    assert(len);
 }
 
-static void vg_strcat( vg_str *str, const char *append ){
-   if( !append ) return;
-   if( str->i == -1 ) return;
+static void vg_strfree( vg_str *str ){
+   if( str->len == -1 ){
+      if( str->buffer ){
+         vg_str_dynamic *arr = (vg_str_dynamic *)str->buffer;
+         free( arr-1 );
+
+         str->buffer = NULL;
+         str->i = 0;
+      }
+   }
+}
 
-   for( u32 i=0; str->i < str->len; str->i ++, i ++ ){
-      str->buffer[ str->i ] = append[ i ];
+/*
+ * Double the size of the dynamically allocated string. If unallocated, alloc of
+ * 16 bytes minimum.
+ */
+static i32 vg_str_dynamic_grow( vg_str *str ){
+   if( str->buffer ){
+      vg_str_dynamic *hdr = ((vg_str_dynamic *)str->buffer) - 1;
+      i32 total = (hdr->len + sizeof(vg_str_dynamic)) * 2;
+      hdr = realloc( hdr, total );
+      hdr->len = total - sizeof(vg_str_dynamic);
+      str->buffer = (char *)(hdr+1);
+      return hdr->len;
+   }
+   else {
+      vg_str_dynamic *hdr = malloc(16);
+      hdr->len = 16-sizeof(vg_str_dynamic);
+      str->buffer = (char *)(hdr+1);
+      str->buffer[0] = '\0';
+      return hdr->len;
+   }
+}
 
-      if( append[ i ] == '\0' )
+/*
+ * Append null terminated string to vg_str 
+ */
+static void vg_strcat( vg_str *str, const char *append ){
+   if( !append || (str->i == -1) ) return;
+
+   i32 max = vg_str_storage( str ),
+       i   = 0;
+
+append:
+   if( str->i == max ){
+      if( str->len == -1 )
+         max = vg_str_dynamic_grow( str );
+      else{
+         str->i = -1;
+         str->buffer[ max-1 ] = '\0';
          return;
+      }
    }
 
-   /* overflow */
-   str->buffer[ str->len-1 ] = '\0';
-   str->i = -1;
+   char c = append[ i ++ ];
+   str->buffer[ str->i ] = c;
+
+   if( c == '\0' )
+      return;
+
+   str->i ++;
+   goto append;
 }
 
+/* 
+ * Append character to vg_str 
+ */
 static void vg_strcatch( vg_str *str, char c ){
-   if( str->i == -1 ) return;
-   if( (str->i + 2) > str->len ){
-      str->i = -1;
-      return;
-   }
-   str->buffer[ str->i ++ ] = c;
-   str->buffer[ str->i ] = '\0';
+   vg_strcat( str, (char[]){ c, '\0' } );
 }
 
-/* FIXME: Negative numbers */
+/* 
+ * FIXME: Negative numbers
+ */
 static void vg_strcati32( vg_str *str, i32 value ){
    if( value ){
       char temp[32];
@@ -154,11 +229,17 @@ static void vg_strcati32r( vg_str *str, i32 value, i32 n, char alt ){
    vg_strcat( str, temp );
 }
 
+/*
+ * Returns 1 if string did not overflow while building
+ */
 static int vg_strgood( vg_str *str ){
    if( str->i == -1 ) return 0;
    else return 1;
 }
 
+/*
+ * Returns pointer to first instance of character
+ */
 static char *vg_strch( vg_str *str, char c ){
    char *ptr = NULL;
    for( i32 i=0; i<str->i; i++ ){
-- 
2.25.1