allow nested [] in CLI args

this now works:

	vips copy x y.dz[suffix=.jpg[Q=90]]

ChangeLog

@@ -4,6 +4,7 @@
 - added @n option to pdfload, thanks andris
 - dzsave won't write empty tiles in google mode, thanks bverem, perog,
   felixbuenemann
+- allow nested [] in CLI args
 
 15/4/16 started 8.3.1
 - rename vips wrapper script, it was still vips-8.2, thanks Benjamin

TODO

@@ -1,8 +1,3 @@
-- this seems to not work:
-
-	$ vips copy k2.jpg x.dz[suffix=.jpg[Q=90]]
-	dzsave: not , or ) after parameter
-
 - add more webp tests to py suite
 
 - try moving some more of the CLI tests to py

libvips/include/vips/util.h

@@ -281,6 +281,10 @@ const char *vips__token_must( const char *buffer, VipsToken *token,
 	char *string, int size );
 const char *vips__token_need( const char *buffer, VipsToken need_token, 
 	char *string, int size );
+const char *vips__token_segment( const char *p, VipsToken *token, 
+	char *string, int size );
+const char *vips__token_segment_need( const char *p, VipsToken need_token, 
+	char *string, int size );
 const char *vips__find_rightmost_brackets( const char *p );
 void vips__filename_split8( const char *name, 
 	char *filename, char *option_string );

libvips/iofuncs/object.c

@@ -2282,7 +2282,7 @@ vips_object_set_args( VipsObject *object, const char *p )
 		string, VIPS_PATH_MAX )) )
 		return( -1 );
 
-	if( !(p = vips__token_must( p, &token, string, VIPS_PATH_MAX )) )
+	if( !(p = vips__token_segment( p, &token, string, VIPS_PATH_MAX )) )
 		return( -1 );
 
 	for(;;) {
@@ -2295,19 +2295,20 @@ vips_object_set_args( VipsObject *object, const char *p )
 			return( -1 );
 		}
 
-		/* We have to look for a '=', ')' or a ',' to see if string is
+		/* We have to look for a '=', ']' or a ',' to see if string is
 		 * a param name or a value.
 		 */
-		if( !(p = vips__token_must( p, &token, 
+		if( !(p = vips__token_segment( p, &token, 
 			string2, VIPS_PATH_MAX )) )
 			return( -1 );
 		if( token == VIPS_TOKEN_EQUALS ) {
-			if( !(p = vips__token_need( p, VIPS_TOKEN_STRING,
+			if( !(p = vips__token_segment_need( p, VIPS_TOKEN_STRING,
 				string2, VIPS_PATH_MAX )) )
 				return( -1 );
 			if( vips_object_set_argument_from_string( object, 
 				string, string2 ) )
 				return( -1 );
+
 			if( !(p = vips__token_must( p, &token,
 				string2, VIPS_PATH_MAX )) )
 				return( -1 );

libvips/iofuncs/util.c

@@ -1232,19 +1232,20 @@ vips__token_get( const char *p, VipsToken *token, char *string, int size )
 	default:
 		/* It's an unquoted string: read up to the next non-string
 		 * character. We don't allow two strings next to each other,
-		 * so the next break must be bracket, equals, comma.
+		 * so the next break must be brackets, equals, comma.
 		 */
 		*token = VIPS_TOKEN_STRING;
-		n = strcspn( p, "[]=," );
-		i = VIPS_MIN( n, size );
+		q = p + strcspn( p, "[]=," );
+
+		i = VIPS_MIN( q - p, size );
 		vips_strncpy( string, p, i + 1 );
-		p += n;
+		p = q;
 
 		/* We remove leading whitespace, so we trim trailing
 		 * whitespace from unquoted strings too. Only if the string
 		 * hasn't been truncated.
 		 */
-		if( i == n ) 
+		if( i != size ) 
 			while( i > 0 && isspace( string[i - 1] ) ) {
 				string[i - 1] = '\0';
 				i--;
@@ -1291,6 +1292,76 @@ vips__token_need( const char *p, VipsToken need_token,
 	return( p );
 }
 
+/* Fetch a token. If it's a string token terminated by a '[', fetch up to the
+ * matching ']' as well, for example ".jpg[Q=90]".
+ *
+ * Return NULL for end of tokens.
+ */
+const char *
+vips__token_segment( const char *p, VipsToken *token, 
+	char *string, int size )
+{
+	const char *q;
+
+	if( !(q = vips__token_must( p, token, string, size )) )
+		return( NULL ); 
+
+	/* If we stopped on [, read up to the matching ]. 
+	 */
+	if( *token == VIPS_TOKEN_STRING &&
+		q[0] == '[' ) {
+		VipsToken sub_token;
+		char sub_string[VIPS_PATH_MAX];
+		int depth;
+		int i; 
+
+		depth = 0;
+		do {
+			if( !(q = vips__token_must( q, &sub_token, 
+				sub_string, VIPS_PATH_MAX )) )
+				return( NULL ); 
+
+			switch( sub_token ) {
+			case VIPS_TOKEN_LEFT:
+				depth += 1;
+				break;
+
+			case VIPS_TOKEN_RIGHT:
+				depth -= 1;
+				break;
+
+			default:
+				break;
+			}
+		} while( !(sub_token == VIPS_TOKEN_RIGHT && depth == 0) );
+
+		i = VIPS_MIN( q - p, size );
+		vips_strncpy( string, p, i + 1 );
+	}
+
+	return( q ); 
+}
+
+/* We expect a certain segment.
+ */
+const char *
+vips__token_segment_need( const char *p, VipsToken need_token, 
+	char *string, int size )
+{
+	VipsToken token;
+
+	if( !(p = vips__token_segment( p, &token, string, size )) ) 
+		return( NULL );
+	if( token != need_token ) {
+		vips_error( "get_token", _( "expected %s, saw %s" ), 
+			vips_enum_nick( VIPS_TYPE_TOKEN, need_token ),
+			vips_enum_nick( VIPS_TYPE_TOKEN, token ) );
+		return( NULL );
+	}
+
+	return( p );
+}
+
 /* Maximum number of tokens we allow in a filename. Surely this will be
  * plenty.
  */