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<?php
/*
* Copyright 2013 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace Google\Utils;
/**
* Implementation of levels 1-3 of the URI Template spec.
* @see http://tools.ietf.org/html/rfc6570
*/
class UriTemplate
{
const TYPE_MAP = "1";
const TYPE_LIST = "2";
const TYPE_SCALAR = "4";
/**
* @var $operators array
* These are valid at the start of a template block to
* modify the way in which the variables inside are
* processed.
*/
private $operators = array(
"+" => "reserved",
"/" => "segments",
"." => "dotprefix",
"#" => "fragment",
";" => "semicolon",
"?" => "form",
"&" => "continuation"
);
/**
* @var reserved array
* These are the characters which should not be URL encoded in reserved
* strings.
*/
private $reserved = array(
"=", ",", "!", "@", "|", ":", "/", "?", "#",
"[", "]",'$', "&", "'", "(", ")", "*", "+", ";"
);
private $reservedEncoded = array(
"%3D", "%2C", "%21", "%40", "%7C", "%3A", "%2F", "%3F",
"%23", "%5B", "%5D", "%24", "%26", "%27", "%28", "%29",
"%2A", "%2B", "%3B"
);
public function parse($string, array $parameters)
{
return $this->resolveNextSection($string, $parameters);
}
/**
* This function finds the first matching {...} block and
* executes the replacement. It then calls itself to find
* subsequent blocks, if any.
*/
private function resolveNextSection($string, $parameters)
{
$start = strpos($string, "{");
if ($start === false) {
return $string;
}
$end = strpos($string, "}");
if ($end === false) {
return $string;
}
$string = $this->replace($string, $start, $end, $parameters);
return $this->resolveNextSection($string, $parameters);
}
private function replace($string, $start, $end, $parameters)
{
// We know a data block will have {} round it, so we can strip that.
$data = substr($string, $start + 1, $end - $start - 1);
// If the first character is one of the reserved operators, it effects
// the processing of the stream.
if (isset($this->operators[$data[0]])) {
$op = $this->operators[$data[0]];
$data = substr($data, 1);
$prefix = "";
$prefix_on_missing = false;
switch ($op) {
case "reserved":
// Reserved means certain characters should not be URL encoded
$data = $this->replaceVars($data, $parameters, ",", null, true);
break;
case "fragment":
// Comma separated with fragment prefix. Bare values only.
$prefix = "#";
$prefix_on_missing = true;
$data = $this->replaceVars($data, $parameters, ",", null, true);
break;
case "segments":
// Slash separated data. Bare values only.
$prefix = "/";
$data =$this->replaceVars($data, $parameters, "/");
break;
case "dotprefix":
// Dot separated data. Bare values only.
$prefix = ".";
$prefix_on_missing = true;
$data = $this->replaceVars($data, $parameters, ".");
break;
case "semicolon":
// Semicolon prefixed and separated. Uses the key name
$prefix = ";";
$data = $this->replaceVars($data, $parameters, ";", "=", false, true, false);
break;
case "form":
// Standard URL format. Uses the key name
$prefix = "?";
$data = $this->replaceVars($data, $parameters, "&", "=");
break;
case "continuation":
// Standard URL, but with leading ampersand. Uses key name.
$prefix = "&";
$data = $this->replaceVars($data, $parameters, "&", "=");
break;
}
// Add the initial prefix character if data is valid.
if ($data || ($data !== false && $prefix_on_missing)) {
$data = $prefix . $data;
}
} else {
// If no operator we replace with the defaults.
$data = $this->replaceVars($data, $parameters);
}
// This is chops out the {...} and replaces with the new section.
return substr($string, 0, $start) . $data . substr($string, $end + 1);
}
private function replaceVars(
$section,
$parameters,
$sep = ",",
$combine = null,
$reserved = false,
$tag_empty = false,
$combine_on_empty = true
) {
if (strpos($section, ",") === false) {
// If we only have a single value, we can immediately process.
return $this->combine(
$section,
$parameters,
$sep,
$combine,
$reserved,
$tag_empty,
$combine_on_empty
);
} else {
// If we have multiple values, we need to split and loop over them.
// Each is treated individually, then glued together with the
// separator character.
$vars = explode(",", $section);
return $this->combineList(
$vars,
$sep,
$parameters,
$combine,
$reserved,
false, // Never emit empty strings in multi-param replacements
$combine_on_empty
);
}
}
public function combine(
$key,
$parameters,
$sep,
$combine,
$reserved,
$tag_empty,
$combine_on_empty
) {
$length = false;
$explode = false;
$skip_final_combine = false;
$value = false;
// Check for length restriction.
if (strpos($key, ":") !== false) {
list($key, $length) = explode(":", $key);
}
// Check for explode parameter.
if ($key[strlen($key) - 1] == "*") {
$explode = true;
$key = substr($key, 0, -1);
$skip_final_combine = true;
}
// Define the list separator.
$list_sep = $explode ? $sep : ",";
if (isset($parameters[$key])) {
$data_type = $this->getDataType($parameters[$key]);
switch ($data_type) {
case self::TYPE_SCALAR:
$value = $this->getValue($parameters[$key], $length);
break;
case self::TYPE_LIST:
$values = array();
foreach ($parameters[$key] as $pkey => $pvalue) {
$pvalue = $this->getValue($pvalue, $length);
if ($combine && $explode) {
$values[$pkey] = $key . $combine . $pvalue;
} else {
$values[$pkey] = $pvalue;
}
}
$value = implode($list_sep, $values);
if ($value == '') {
return '';
}
break;
case self::TYPE_MAP:
$values = array();
foreach ($parameters[$key] as $pkey => $pvalue) {
$pvalue = $this->getValue($pvalue, $length);
if ($explode) {
$pkey = $this->getValue($pkey, $length);
$values[] = $pkey . "=" . $pvalue; // Explode triggers = combine.
} else {
$values[] = $pkey;
$values[] = $pvalue;
}
}
$value = implode($list_sep, $values);
if ($value == '') {
return false;
}
break;
}
} else if ($tag_empty) {
// If we are just indicating empty values with their key name, return that.
return $key;
} else {
// Otherwise we can skip this variable due to not being defined.
return false;
}
if ($reserved) {
$value = str_replace($this->reservedEncoded, $this->reserved, $value);
}
// If we do not need to include the key name, we just return the raw
// value.
if (!$combine || $skip_final_combine) {
return $value;
}
// Else we combine the key name: foo=bar, if value is not the empty string.
return $key . ($value != '' || $combine_on_empty ? $combine . $value : '');
}
/**
* Return the type of a passed in value
*/
private function getDataType($data)
{
if (is_array($data)) {
reset($data);
if (key($data) !== 0) {
return self::TYPE_MAP;
}
return self::TYPE_LIST;
}
return self::TYPE_SCALAR;
}
/**
* Utility function that merges multiple combine calls
* for multi-key templates.
*/
private function combineList(
$vars,
$sep,
$parameters,
$combine,
$reserved,
$tag_empty,
$combine_on_empty
) {
$ret = array();
foreach ($vars as $var) {
$response = $this->combine(
$var,
$parameters,
$sep,
$combine,
$reserved,
$tag_empty,
$combine_on_empty
);
if ($response === false) {
continue;
}
$ret[] = $response;
}
return implode($sep, $ret);
}
/**
* Utility function to encode and trim values
*/
private function getValue($value, $length)
{
if ($length) {
$value = substr($value, 0, $length);
}
$value = rawurlencode($value);
return $value;
}
}
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