Viewing file:  RelativeResourceTemplate.php (15.68 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
<?php
/*
* Copyright 2018 Google LLC
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
namespace Google\ApiCore\ResourceTemplate;
use Google\ApiCore\ValidationException;
/**
* Represents a relative resource template, meaning that it will never contain a leading slash or
* trailing verb (":<verb>").
*
* Examples:
* projects
* projects/{project}
* foo/{bar=**}/fizz/*
*
* Templates use the syntax of the API platform; see
* https://github.com/googleapis/api-common-protos/blob/master/google/api/http.proto
* for details. A template consists of a sequence of literals, wildcards, and variable bindings,
* where each binding can have a sub-path. A string representation can be parsed into an
* instance of AbsoluteResourceTemplate, which can then be used to perform matching and instantiation.
*/
class RelativeResourceTemplate implements ResourceTemplateInterface
{
/** @var Segment[] $segments */
private $segments;
/**
* RelativeResourceTemplate constructor.
*
* @param string $path
* @throws ValidationException
*/
public function __construct($path)
{
if (empty($path)) {
$msg = sprintf(
"Cannot construct RelativeResourceTemplate from %s string",
is_null($path) ? "null" : "empty"
);
throw new ValidationException($msg);
}
$this->segments = Parser::parseSegments($path);
$doubleWildcardCount = self::countDoubleWildcards($this->segments);
if ($doubleWildcardCount > 1) {
throw new ValidationException(
"Cannot parse '$path': cannot contain more than one path wildcard"
);
}
// Check for duplicate keys
$keys = [];
foreach ($this->segments as $segment) {
if ($segment->getSegmentType() === Segment::VARIABLE_SEGMENT) {
if (isset($keys[$segment->getKey()])) {
throw new ValidationException(
"Duplicate key '{$segment->getKey()}' in path $path"
);
}
$keys[$segment->getKey()] = true;
}
}
}
/**
* @inheritdoc
*/
public function __toString()
{
return self::renderSegments($this->segments);
}
/**
* @inheritdoc
*/
public function render(array $bindings)
{
$literalSegments = [];
$keySegmentTuples = self::buildKeySegmentTuples($this->segments);
foreach ($keySegmentTuples as list($key, $segment)) {
/** @var Segment $segment */
if ($segment->getSegmentType() === Segment::LITERAL_SEGMENT) {
$literalSegments[] = $segment;
continue;
}
if (!array_key_exists($key, $bindings)) {
throw $this->renderingException($bindings, "missing required binding '$key' for segment '$segment'");
}
$value = $bindings[$key];
if ($segment->matches($value)) {
$literalSegments[] = new Segment(
Segment::LITERAL_SEGMENT,
$value,
$segment->getValue(),
$segment->getTemplate(),
$segment->getSeparator()
);
} else {
$valueString = is_null($value) ? "null" : "'$value'";
throw $this->renderingException(
$bindings,
"expected binding '$key' to match segment '$segment', instead got $valueString"
);
}
}
return self::renderSegments($literalSegments);
}
/**
* @inheritdoc
*/
public function matches($path)
{
try {
$this->match($path);
return true;
} catch (ValidationException $ex) {
return false;
}
}
/**
* @inheritdoc
*/
public function match($path)
{
// High level strategy for matching:
// - Build a list of Segments from our template, where any variable segments are
// flattened into a single, non-nested list
// - Break $path into pieces based on '/'.
// - Use the segments to further subdivide the pieces using any applicable non-slash separators.
// - Match pieces of the path with Segments in the flattened list
// In order to build correct bindings after we match the $path against our template, we
// need to (a) calculate the correct positional keys for our wildcards, and (b) maintain
// information about the variable identifier of any flattened segments. To do this, we
// build a list of [string, Segment] tuples, where the string component is the appropriate
// key.
$keySegmentTuples = self::buildKeySegmentTuples($this->segments);
$flattenedKeySegmentTuples = self::flattenKeySegmentTuples($keySegmentTuples);
$flattenedKeySegmentTuplesCount = count($flattenedKeySegmentTuples);
assert($flattenedKeySegmentTuplesCount > 0);
$slashPathPieces = explode('/', $path);
$pathPieces = [];
$pathPiecesIndex = 0;
$startIndex = 0;
$slashPathPiecesCount = count($slashPathPieces);
$doubleWildcardPieceCount = $slashPathPiecesCount - $flattenedKeySegmentTuplesCount + 1;
for ($i = 0; $i < count($flattenedKeySegmentTuples); $i++) {
$segmentKey = $flattenedKeySegmentTuples[$i][0];
$segment = $flattenedKeySegmentTuples[$i][1];
// In our flattened list of segments, we should never encounter a variable segment
assert($segment->getSegmentType() !== Segment::VARIABLE_SEGMENT);
if ($segment->getSegmentType() == Segment::DOUBLE_WILDCARD_SEGMENT) {
$pathPiecesForSegment = array_slice($slashPathPieces, $pathPiecesIndex, $doubleWildcardPieceCount);
$pathPiece = implode('/', $pathPiecesForSegment);
$pathPiecesIndex += $doubleWildcardPieceCount;
$pathPieces[] = $pathPiece;
continue;
}
if ($segment->getSegmentType() == Segment::WILDCARD_SEGMENT) {
if ($pathPiecesIndex >= $slashPathPiecesCount) {
break;
}
}
if ($segment->getSeparator() === '/') {
if ($pathPiecesIndex >= $slashPathPiecesCount) {
throw $this->matchException($path, "segment and path length mismatch");
}
$pathPiece = substr($slashPathPieces[$pathPiecesIndex++], $startIndex);
$startIndex = 0;
} else {
$rawPiece = substr($slashPathPieces[$pathPiecesIndex], $startIndex);
$pathPieceLength = strpos($rawPiece, $segment->getSeparator());
$pathPiece = substr($rawPiece, 0, $pathPieceLength);
$startIndex += $pathPieceLength + 1;
}
$pathPieces[] = $pathPiece;
}
if ($flattenedKeySegmentTuples[$i - 1][1]->getSegmentType() !== Segment::DOUBLE_WILDCARD_SEGMENT) {
// Process any remaining pieces. The binding logic will throw exceptions for any invalid paths.
for (; $pathPiecesIndex < count($slashPathPieces); $pathPiecesIndex++) {
$pathPieces[] = $slashPathPieces[$pathPiecesIndex];
}
}
$pathPiecesCount = count($pathPieces);
// We would like to match pieces of our path 1:1 with the segments of our template. However,
// this is confounded by the presence of double wildcards ('**') in the template, which can
// match multiple segments in the path.
// Because there can only be one '**' present, we can determine how many segments it must
// match by examining the difference in count between the template segments and the
// path pieces.
if ($pathPiecesCount < $flattenedKeySegmentTuplesCount) {
// Each segment in $flattenedKeyedSegments must consume at least one
// segment in $pathSegments, so matching must fail.
throw $this->matchException($path, "path does not contain enough segments to be matched");
}
$doubleWildcardPieceCount = $pathPiecesCount - $flattenedKeySegmentTuplesCount + 1;
$bindings = [];
$pathPiecesIndex = 0;
/** @var Segment $segment */
foreach ($flattenedKeySegmentTuples as list($segmentKey, $segment)) {
$pathPiece = $pathPieces[$pathPiecesIndex++];
if (!$segment->matches($pathPiece)) {
throw $this->matchException($path, "expected path element matching '$segment', got '$pathPiece'");
}
// If we have a valid key, add our $pathPiece to the $bindings array. Note that there
// may be multiple copies of the same $segmentKey. This is because a flattened variable
// segment can match multiple pieces from the path. We can add these to an array and
// collapse them all once the bindings are complete.
if (isset($segmentKey)) {
$bindings += [$segmentKey => []];
$bindings[$segmentKey][] = $pathPiece;
}
}
// It is possible that we have left over path pieces, which can occur if our template does
// not have a double wildcard. In that case, the match should fail.
if ($pathPiecesIndex !== $pathPiecesCount) {
throw $this->matchException($path, "expected end of path, got '$pathPieces[$pathPiecesIndex]'");
}
// Collapse the bindings from lists into strings
$collapsedBindings = [];
foreach ($bindings as $key => $boundPieces) {
$collapsedBindings[$key] = implode('/', $boundPieces);
}
return $collapsedBindings;
}
private function matchException($path, $reason)
{
return new ValidationException("Could not match path '$path' to template '$this': $reason");
}
private function renderingException($bindings, $reason)
{
$bindingsString = print_r($bindings, true);
return new ValidationException(
"Error rendering '$this': $reason\n" .
"Provided bindings: $bindingsString"
);
}
/**
* @param Segment[] $segments
* @param string|null $separator An optional string separator
* @return array[] A list of [string, Segment] tuples
*/
private static function buildKeySegmentTuples(array $segments, $separator = null)
{
$keySegmentTuples = [];
$positionalArgumentCounter = 0;
foreach ($segments as $segment) {
switch ($segment->getSegmentType()) {
case Segment::WILDCARD_SEGMENT:
case Segment::DOUBLE_WILDCARD_SEGMENT:
$positionalKey = "\$$positionalArgumentCounter";
$positionalArgumentCounter++;
$newSegment = $segment;
if ($separator !== null) {
$newSegment = new Segment(
$segment->getSegmentType(),
$segment->getValue(),
$segment->getKey(),
$segment->getTemplate(),
$separator
);
}
$keySegmentTuples[] = [$positionalKey, $newSegment];
break;
default:
$keySegmentTuples[] = [$segment->getKey(), $segment];
}
}
return $keySegmentTuples;
}
/**
* @param array[] A list of [string, Segment] tuples
* @return array[] A list of [string, Segment] tuples
*/
private static function flattenKeySegmentTuples(array $keySegmentTuples)
{
$flattenedKeySegmentTuples = [];
foreach ($keySegmentTuples as list($key, $segment)) {
/** @var Segment $segment */
switch ($segment->getSegmentType()) {
case Segment::VARIABLE_SEGMENT:
// For segment variables, replace the segment with the segments of its children
$template = $segment->getTemplate();
$nestedKeySegmentTuples = self::buildKeySegmentTuples(
$template->segments,
$segment->getSeparator()
);
foreach ($nestedKeySegmentTuples as list($nestedKey, $nestedSegment)) {
/** @var Segment $nestedSegment */
// Nested variables are not allowed
assert($nestedSegment->getSegmentType() !== Segment::VARIABLE_SEGMENT);
// Insert the nested segment with key set to the outer key of the
// parent variable segment
$flattenedKeySegmentTuples[] = [$key, $nestedSegment];
}
break;
default:
// For all other segments, don't change the key or segment
$flattenedKeySegmentTuples[] = [$key, $segment];
}
}
return $flattenedKeySegmentTuples;
}
/**
* @param Segment[] $segments
* @return int
*/
private static function countDoubleWildcards(array $segments)
{
$doubleWildcardCount = 0;
foreach ($segments as $segment) {
switch ($segment->getSegmentType()) {
case Segment::DOUBLE_WILDCARD_SEGMENT:
$doubleWildcardCount++;
break;
case Segment::VARIABLE_SEGMENT:
$doubleWildcardCount += self::countDoubleWildcards($segment->getTemplate()->segments);
break;
}
}
return $doubleWildcardCount;
}
/**
* Joins segments using their separators.
* @param array $segmentsToRender
* @return string
*/
private static function renderSegments($segmentsToRender)
{
$renderResult = "";
for ($i = 0; $i < count($segmentsToRender); $i++) {
$segment = $segmentsToRender[$i];
$renderResult .= $segment;
if ($i < count($segmentsToRender) - 1) {
$renderResult .= $segment->getSeparator();
}
}
return $renderResult;
}
}
|