[RFC] Add json_encode indent parameter

ext/json/json.c

@@ -142,13 +142,14 @@ static PHP_MINFO_FUNCTION(json)
 }
 /* }}} */
 
-PHP_JSON_API zend_result php_json_encode_ex(smart_str *buf, zval *val, int options, zend_long depth) /* {{{ */
+PHP_JSON_API zend_result php_json_encode_ex(smart_str *buf, zval *val, int options, zend_long depth, zend_string *indent_str) /* {{{ */
 {
 	php_json_encoder encoder;
 	zend_result return_code;
 
 	php_json_encode_init(&encoder);
 	encoder.max_depth = depth;
+	encoder.indent_str = indent_str;
 
 	return_code = php_json_encode_zval(buf, val, options, &encoder);
 	JSON_G(error_code) = encoder.error_code;
@@ -159,7 +160,13 @@ PHP_JSON_API zend_result php_json_encode_ex(smart_str *buf, zval *val, int optio
 
 PHP_JSON_API zend_result php_json_encode(smart_str *buf, zval *val, int options) /* {{{ */
 {
-	return php_json_encode_ex(buf, val, options, JSON_G(encode_max_depth));
+	zend_string *indent_str = zend_string_init("    ", strlen("    "), 0);
+
+	int result = php_json_encode_ex(buf, val, options, JSON_G(encode_max_depth), indent_str);
+
+	zend_string_release(indent_str);
+
+	return result;
 }
 /* }}} */
 
@@ -223,20 +230,42 @@ PHP_FUNCTION(json_encode)
 	zval *parameter;
 	php_json_encoder encoder;
 	smart_str buf = {0};
+	zend_string *indent_str = NULL;
 	zend_long options = 0;
 	zend_long depth = PHP_JSON_PARSER_DEFAULT_DEPTH;
+	zend_long indent = PHP_JSON_ENCODER_DEFAULT_INDENT;
 
-	ZEND_PARSE_PARAMETERS_START(1, 3)
+	ZEND_PARSE_PARAMETERS_START(1, 4)
 		Z_PARAM_ZVAL(parameter)
 		Z_PARAM_OPTIONAL
 		Z_PARAM_LONG(options)
 		Z_PARAM_LONG(depth)
+		Z_PARAM_LONG(indent)
 	ZEND_PARSE_PARAMETERS_END();
 
+	if (indent < 0) {
+		zend_argument_value_error(4, "must be a number greater than or equal to 0");
+		RETURN_THROWS();
+	}
+
+	if (indent > 0) {
+		// Generate indent_str
+		indent_str = zend_string_alloc(indent, 0);
+		for (zend_long i = 0; i < indent; i++)
+			ZSTR_VAL(indent_str)[i] = ' ';
+	}
+
 	php_json_encode_init(&encoder);
 	encoder.max_depth = (int)depth;
+	encoder.indent_str = indent_str;
+
 	php_json_encode_zval(&buf, parameter, (int)options, &encoder);
 
+	if (indent > 0 && indent_str) {
+		// If the indent_str was generated locally, we need to release it.
+		zend_string_release(indent_str);
+	}
+
 	if (!(options & PHP_JSON_THROW_ON_ERROR) || (options & PHP_JSON_PARTIAL_OUTPUT_ON_ERROR)) {
 		JSON_G(error_code) = encoder.error_code;
 		if (encoder.error_code != PHP_JSON_ERROR_NONE && !(options & PHP_JSON_PARTIAL_OUTPUT_ON_ERROR)) {

ext/json/json.stub.php

@@ -3,7 +3,7 @@
 /** @generate-class-entries */
 
 /** @refcount 1 */
-function json_encode(mixed $value, int $flags = 0, int $depth = 512): string|false {}
+function json_encode(mixed $value, int $flags = 0, int $depth = 512, int $indent = 4): string|false {}
 
 function json_decode(string $json, ?bool $associative = null, int $depth = 512, int $flags = 0): mixed {}
 

ext/json/json_encoder.c

@@ -59,11 +59,16 @@ static inline void php_json_pretty_print_char(smart_str *buf, int options, char
 
 static inline void php_json_pretty_print_indent(smart_str *buf, int options, php_json_encoder *encoder) /* {{{ */
 {
-	int i;
+	size_t i;
+
+	size_t indent_length = encoder->indent_str ? ZSTR_LEN(encoder->indent_str) : 0;
+	if (!indent_length) {
+		return;
+	}
 
 	if (options & PHP_JSON_PRETTY_PRINT) {
 		for (i = 0; i < encoder->depth; ++i) {
-			smart_str_appendl(buf, "    ", 4);
+			smart_str_appendl(buf, ZSTR_VAL(encoder->indent_str), indent_length);
 		}
 	}
 }

ext/json/php_json.h

@@ -84,9 +84,13 @@ typedef enum {
 /* default depth */
 #define PHP_JSON_PARSER_DEFAULT_DEPTH 512
 
+/* default indent */
+#define PHP_JSON_ENCODER_DEFAULT_INDENT 4
+
 ZEND_BEGIN_MODULE_GLOBALS(json)
 	int encoder_depth;
 	int encode_max_depth;
+	size_t encoder_indent;
 	php_json_error_code error_code;
 ZEND_END_MODULE_GLOBALS(json)
 
@@ -97,7 +101,7 @@ PHP_JSON_API ZEND_EXTERN_MODULE_GLOBALS(json)
 ZEND_TSRMLS_CACHE_EXTERN()
 #endif
 
-PHP_JSON_API zend_result php_json_encode_ex(smart_str *buf, zval *val, int options, zend_long depth);
+PHP_JSON_API zend_result php_json_encode_ex(smart_str *buf, zval *val, int options, zend_long depth, zend_string *indent_str);
 PHP_JSON_API zend_result php_json_encode(smart_str *buf, zval *val, int options);
 PHP_JSON_API zend_result php_json_decode_ex(zval *return_value, const char *str, size_t str_len, zend_long options, zend_long depth);
 

ext/json/php_json_encoder.h

@@ -26,6 +26,7 @@ struct _php_json_encoder {
 	int depth;
 	int max_depth;
 	php_json_error_code error_code;
+	zend_string *indent_str;
 };
 
 static inline void php_json_encode_init(php_json_encoder *encoder)

ext/json/tests/json_encode_pretty_print3.phpt

@@ -0,0 +1,24 @@
+--TEST--
+json_encode() with JSON_PRETTY_PRINT with 2 spaces string indentation
+--FILE--
+<?php
+
+$data = [
+    'key' => 4,
+    'other_key' => [0, 1, 2, 3]
+];
+
+echo json_encode($data, JSON_PRETTY_PRINT, 512, 2);
+
+?>
+--EXPECT--
+{
+  "key": 4,
+  "other_key": [
+    0,
+    1,
+    2,
+    3
+  ]
+}
+

ext/json/tests/json_encode_pretty_print_indent_error.phpt

@@ -0,0 +1,25 @@
+--TEST--
+json_encode() with JSON_PRETTY_PRINT with negative indentation
+--FILE--
+<?php
+echo "*** Testing json_encode() : error conditions ***\n";
+
+echo "\n-- Testing json_encode() function (JSON_PRETTY_PRINT) with negative indentation --\n";
+
+$data = [
+    'key' => 4,
+    'other_key' => [0, 1, 2, 3]
+];
+
+try {
+  echo json_encode($data, JSON_PRETTY_PRINT, 512, -2);
+} catch (\ValueError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
+
+?>
+--EXPECT--
+*** Testing json_encode() : error conditions ***
+
+-- Testing json_encode() function (JSON_PRETTY_PRINT) with negative indentation --
+json_encode(): Argument #4 ($indent) must be a number greater than or equal to 0