/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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.
 */

package org.springframework.web.util.pattern;

import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.http.server.PathContainer;
import org.springframework.http.server.PathContainer.Element;
import org.springframework.http.server.PathContainer.Separator;
import org.springframework.lang.Nullable;
import org.springframework.util.CollectionUtils;
import org.springframework.util.MultiValueMap;
import org.springframework.util.StringUtils;

Representation of a parsed path pattern. Includes a chain of path elements
for fast matching and accumulates computed state for quick comparison of
patterns.
PathPattern matches URL paths using the following rules:


? matches one character
* matches zero or more characters within a path segment
** matches zero or more path segments until the end of the path
{spring} matches a path segment and captures it as a variable named "spring"
{spring:[a-z]+} matches the regexp [a-z]+ as a path variable named "spring"
{*spring} matches zero or more path segments until the end of the path
and captures it as a variable named "spring"

Examples

/pages/t?st.html — matches /pages/test.html but also /pages/tast.html but not /pages/toast.html
/resources/*.png — matches all .png files in the resources directory
/resources/** — matches all files underneath the /resources/ path, including /resources/image.png and /resources/css/spring.css
/resources/{*path} — matches all files underneath the /resources/ path and captures their relative path in a variable named "path"; /resources/image.png will match with "spring" -> "/image.png", and /resources/css/spring.css will match with "spring" -> "/css/spring.css"
/resources/{filename:\\w+}.dat will match /resources/spring.dat and assign the value "spring" to the filename variable

Author:
Andy Clement, Rossen Stoyanchev
See Also:
PathContainer
Since:
5.0/**
 * Representation of a parsed path pattern. Includes a chain of path elements
 * for fast matching and accumulates computed state for quick comparison of
 * patterns.
 *
 * <p>{@code PathPattern} matches URL paths using the following rules:<br>
 * <ul>
 * <li>{@code ?} matches one character</li>
 * <li>{@code *} matches zero or more characters within a path segment</li>
 * <li>{@code **} matches zero or more <em>path segments</em> until the end of the path</li>
 * <li>{@code {spring}} matches a <em>path segment</em> and captures it as a variable named "spring"</li>
 * <li>{@code {spring:[a-z]+}} matches the regexp {@code [a-z]+} as a path variable named "spring"</li>
 * <li>{@code {*spring}} matches zero or more <em>path segments</em> until the end of the path
 * and captures it as a variable named "spring"</li>
 * </ul>
 *
 * <h3>Examples</h3>
 * <ul>
 * <li>{@code /pages/t?st.html} &mdash; matches {@code /pages/test.html} but also
 * {@code /pages/tast.html} but not {@code /pages/toast.html}</li>
 * <li>{@code /resources/*.png} &mdash; matches all {@code .png} files in the
 * {@code resources} directory</li>
 * <li><code>/resources/&#42;&#42;</code> &mdash; matches all files
 * underneath the {@code /resources/} path, including {@code /resources/image.png}
 * and {@code /resources/css/spring.css}</li>
 * <li><code>/resources/{&#42;path}</code> &mdash; matches all files
 * underneath the {@code /resources/} path and captures their relative path in
 * a variable named "path"; {@code /resources/image.png} will match with
 * "spring" -> "/image.png", and {@code /resources/css/spring.css} will match
 * with "spring" -> "/css/spring.css"</li>
 * <li>{@code /resources/{filename:\\w+}.dat} will match {@code /resources/spring.dat}
 * and assign the value {@code "spring"} to the {@code filename} variable</li>
 * </ul>
 *
 * @author Andy Clement
 * @author Rossen Stoyanchev
 * @since 5.0
 * @see PathContainer
 */
public class PathPattern implements Comparable<PathPattern> {

	private static final PathContainer EMPTY_PATH = PathContainer.parsePath("");

	
Comparator that sorts patterns by specificity as follows:

Null instances are last.
Catch-all patterns are last.
If both patterns are catch-all, consider the length (longer wins).
Compare wildcard and captured variable count (lower wins).
Consider length (longer wins)

/**
	 * Comparator that sorts patterns by specificity as follows:
	 * <ol>
	 * <li>Null instances are last.
	 * <li>Catch-all patterns are last.
	 * <li>If both patterns are catch-all, consider the length (longer wins).
	 * <li>Compare wildcard and captured variable count (lower wins).
	 * <li>Consider length (longer wins)
	 * </ol>
	 */
	public static final Comparator<PathPattern> SPECIFICITY_COMPARATOR =
			Comparator.nullsLast(
					Comparator.<PathPattern>
							comparingInt(p -> p.isCatchAll() ? 1 : 0)
							.thenComparingInt(p -> p.isCatchAll() ? scoreByNormalizedLength(p) : 0)
							.thenComparingInt(PathPattern::getScore)
							.thenComparingInt(PathPattern::scoreByNormalizedLength)
			);


	
The text of the parsed pattern. /** The text of the parsed pattern. */
	private final String patternString;

	
The parser used to construct this pattern. /** The parser used to construct this pattern. */
	private final PathPatternParser parser;

	
The separator used when parsing the pattern. /** The separator used when parsing the pattern. */
	private final char separator;

	
If this pattern has no trailing slash, allow candidates to include one and still match successfully. /** If this pattern has no trailing slash, allow candidates to include one and still match successfully. */
	private final boolean matchOptionalTrailingSeparator;

	
Will this match candidates in a case sensitive way? (case sensitivity  at parse time). /** Will this match candidates in a case sensitive way? (case sensitivity  at parse time). */
	private final boolean caseSensitive;

	
First path element in the parsed chain of path elements for this pattern. /** First path element in the parsed chain of path elements for this pattern. */
	@Nullable
	private final PathElement head;

	
How many variables are captured in this pattern. /** How many variables are captured in this pattern. */
	private int capturedVariableCount;

	
The normalized length is trying to measure the 'active' part of the pattern. It is computed
by assuming all captured variables have a normalized length of 1. Effectively this means changing
your variable name lengths isn't going to change the length of the active part of the pattern.
Useful when comparing two patterns.
/**
	 * The normalized length is trying to measure the 'active' part of the pattern. It is computed
	 * by assuming all captured variables have a normalized length of 1. Effectively this means changing
	 * your variable name lengths isn't going to change the length of the active part of the pattern.
	 * Useful when comparing two patterns.
	 */
	private int normalizedLength;

	
Does the pattern end with '<separator>'.
/**
	 * Does the pattern end with '&lt;separator&gt;'.
	 */
	private boolean endsWithSeparatorWildcard = false;

	
Score is used to quickly compare patterns. Different pattern components are given different
weights. A 'lower score' is more specific. Current weights:

Captured variables are worth 1
Wildcard is worth 100

/**
	 * Score is used to quickly compare patterns. Different pattern components are given different
	 * weights. A 'lower score' is more specific. Current weights:
	 * <ul>
	 * <li>Captured variables are worth 1
	 * <li>Wildcard is worth 100
	 * </ul>
	 */
	private int score;

	
Does the pattern end with {*...}. /** Does the pattern end with {*...}. */
	private boolean catchAll = false;


	PathPattern(String patternText, PathPatternParser parser, @Nullable PathElement head) {
		this.patternString = patternText;
		this.parser = parser;
		this.separator = parser.getSeparator();
		this.matchOptionalTrailingSeparator = parser.isMatchOptionalTrailingSeparator();
		this.caseSensitive = parser.isCaseSensitive();
		this.head = head;

		// Compute fields for fast comparison
		PathElement elem = head;
		while (elem != null) {
			this.capturedVariableCount += elem.getCaptureCount();
			this.normalizedLength += elem.getNormalizedLength();
			this.score += elem.getScore();
			if (elem instanceof CaptureTheRestPathElement || elem instanceof WildcardTheRestPathElement) {
				this.catchAll = true;
			}
			if (elem instanceof SeparatorPathElement && elem.next != null &&
					elem.next instanceof WildcardPathElement && elem.next.next == null) {
				this.endsWithSeparatorWildcard = true;
			}
			elem = elem.next;
		}
	}


	
Return the original String that was parsed to create this PathPattern.
/**
	 * Return the original String that was parsed to create this PathPattern.
	 */
	public String getPatternString() {
		return this.patternString;
	}

	
Whether this pattern matches the given path.
Params:
pathContainer – the candidate path to attempt to match against
Returns:
true if the path matches this pattern/**
	 * Whether this pattern matches the given path.
	 * @param pathContainer the candidate path to attempt to match against
	 * @return {@code true} if the path matches this pattern
	 */
	public boolean matches(PathContainer pathContainer) {
		if (this.head == null) {
			return !hasLength(pathContainer) ||
				(this.matchOptionalTrailingSeparator && pathContainerIsJustSeparator(pathContainer));
		}
		else if (!hasLength(pathContainer)) {
			if (this.head instanceof WildcardTheRestPathElement || this.head instanceof CaptureTheRestPathElement) {
				pathContainer = EMPTY_PATH; // Will allow CaptureTheRest to bind the variable to empty
			}
			else {
				return false;
			}
		}
		MatchingContext matchingContext = new MatchingContext(pathContainer, false);
		return this.head.matches(0, matchingContext);
	}

	
Match this pattern to the given URI path and return extracted URI template
variables as well as path parameters (matrix variables).
Params:
pathContainer – the candidate path to attempt to match against
Returns:
info object with the extracted variables, or null for no match/**
	 * Match this pattern to the given URI path and return extracted URI template
	 * variables as well as path parameters (matrix variables).
	 * @param pathContainer the candidate path to attempt to match against
	 * @return info object with the extracted variables, or {@code null} for no match
	 */
	@Nullable
	public PathMatchInfo matchAndExtract(PathContainer pathContainer) {
		if (this.head == null) {
			return hasLength(pathContainer) &&
				!(this.matchOptionalTrailingSeparator && pathContainerIsJustSeparator(pathContainer))
				? null : PathMatchInfo.EMPTY;
		}
		else if (!hasLength(pathContainer)) {
			if (this.head instanceof WildcardTheRestPathElement || this.head instanceof CaptureTheRestPathElement) {
				pathContainer = EMPTY_PATH; // Will allow CaptureTheRest to bind the variable to empty
			}
			else {
				return null;
			}
		}
		MatchingContext matchingContext = new MatchingContext(pathContainer, true);
		return this.head.matches(0, matchingContext) ? matchingContext.getPathMatchResult() : null;
	}

	
Match the beginning of the given path and return the remaining portion
not covered by this pattern. This is useful for matching nested routes
where the path is matched incrementally at each level.
Params:
pathContainer – the candidate path to attempt to match against
Returns:
info object with the match result or null for no match/**
	 * Match the beginning of the given path and return the remaining portion
	 * not covered by this pattern. This is useful for matching nested routes
	 * where the path is matched incrementally at each level.
	 * @param pathContainer the candidate path to attempt to match against
	 * @return info object with the match result or {@code null} for no match
	 */
	@Nullable
	public PathRemainingMatchInfo matchStartOfPath(PathContainer pathContainer) {
		if (this.head == null) {
			return new PathRemainingMatchInfo(pathContainer);
		}
		else if (!hasLength(pathContainer)) {
			return null;
		}

		MatchingContext matchingContext = new MatchingContext(pathContainer, true);
		matchingContext.setMatchAllowExtraPath();
		boolean matches = this.head.matches(0, matchingContext);
		if (!matches) {
			return null;
		}
		else {
			PathRemainingMatchInfo info;
			if (matchingContext.remainingPathIndex == pathContainer.elements().size()) {
				info = new PathRemainingMatchInfo(EMPTY_PATH, matchingContext.getPathMatchResult());
			}
			else {
				info = new PathRemainingMatchInfo(pathContainer.subPath(matchingContext.remainingPathIndex),
						matchingContext.getPathMatchResult());
			}
			return info;
		}
	}

	
Determine the pattern-mapped part for the given path.
For example: 

'/docs/cvs/commit.html' and '/docs/cvs/commit.html -> ''
'/docs/*' and '/docs/cvs/commit' -> 'cvs/commit'
'/docs/cvs/*.html' and '/docs/cvs/commit.html -> 'commit.html'
'/docs/**' and '/docs/cvs/commit -> 'cvs/commit'

Notes:

Assumes that matches returns true for the same path but does not enforce this.
Duplicate occurrences of separators within the returned result are removed
Leading and trailing separators are removed from the returned result

Params:
path – a path that matches this pattern
Returns:
the subset of the path that is matched by pattern or "" if none
of it is matched by pattern elements/**
	 * Determine the pattern-mapped part for the given path.
	 * <p>For example: <ul>
	 * <li>'{@code /docs/cvs/commit.html}' and '{@code /docs/cvs/commit.html} -> ''</li>
	 * <li>'{@code /docs/*}' and '{@code /docs/cvs/commit}' -> '{@code cvs/commit}'</li>
	 * <li>'{@code /docs/cvs/*.html}' and '{@code /docs/cvs/commit.html} -> '{@code commit.html}'</li>
	 * <li>'{@code /docs/**}' and '{@code /docs/cvs/commit} -> '{@code cvs/commit}'</li>
	 * </ul>
	 * <p><b>Notes:</b>
	 * <ul>
	 * <li>Assumes that {@link #matches} returns {@code true} for
	 * the same path but does <strong>not</strong> enforce this.
	 * <li>Duplicate occurrences of separators within the returned result are removed
	 * <li>Leading and trailing separators are removed from the returned result
	 * </ul>
	 * @param path a path that matches this pattern
	 * @return the subset of the path that is matched by pattern or "" if none
	 * of it is matched by pattern elements
	 */
	public PathContainer extractPathWithinPattern(PathContainer path) {
		List<Element> pathElements = path.elements();
		int pathElementsCount = pathElements.size();

		int startIndex = 0;
		// Find first path element that is not a separator or a literal (i.e. the first pattern based element)
		PathElement elem = this.head;
		while (elem != null) {
			if (elem.getWildcardCount() != 0 || elem.getCaptureCount() != 0) {
				break;
			}
			elem = elem.next;
			startIndex++;
		}
		if (elem == null) {
			// There is no pattern piece
			return PathContainer.parsePath("");
		}

		// Skip leading separators that would be in the result
		while (startIndex < pathElementsCount && (pathElements.get(startIndex) instanceof Separator)) {
			startIndex++;
		}

		int endIndex = pathElements.size();
		// Skip trailing separators that would be in the result
		while (endIndex > 0 && (pathElements.get(endIndex - 1) instanceof Separator)) {
			endIndex--;
		}

		boolean multipleAdjacentSeparators = false;
		for (int i = startIndex; i < (endIndex - 1); i++) {
			if ((pathElements.get(i) instanceof Separator) && (pathElements.get(i+1) instanceof Separator)) {
				multipleAdjacentSeparators=true;
				break;
			}
		}

		PathContainer resultPath = null;
		if (multipleAdjacentSeparators) {
			// Need to rebuild the path without the duplicate adjacent separators
			StringBuilder buf = new StringBuilder();
			int i = startIndex;
			while (i < endIndex) {
				Element e = pathElements.get(i++);
				buf.append(e.value());
				if (e instanceof Separator) {
					while (i < endIndex && (pathElements.get(i) instanceof Separator)) {
						i++;
					}
				}
			}
			resultPath = PathContainer.parsePath(buf.toString());
		}
		else if (startIndex >= endIndex) {
			resultPath = PathContainer.parsePath("");
		}
		else {
			resultPath = path.subPath(startIndex, endIndex);
		}
		return resultPath;
	}

	
Compare this pattern with a supplied pattern: return -1,0,+1 if this pattern
is more specific, the same or less specific than the supplied pattern.
The aim is to sort more specific patterns first.
/**
	 * Compare this pattern with a supplied pattern: return -1,0,+1 if this pattern
	 * is more specific, the same or less specific than the supplied pattern.
	 * The aim is to sort more specific patterns first.
	 */
	@Override
	public int compareTo(@Nullable PathPattern otherPattern) {
		int result = SPECIFICITY_COMPARATOR.compare(this, otherPattern);
		return (result == 0 && otherPattern != null ?
				this.patternString.compareTo(otherPattern.patternString) : result);
	}

	
Combine this pattern with another. Currently does not produce a new PathPattern, just produces a new string.
/**
	 * Combine this pattern with another. Currently does not produce a new PathPattern, just produces a new string.
	 */
	public PathPattern combine(PathPattern pattern2string) {
		// If one of them is empty the result is the other. If both empty the result is ""
		if (!StringUtils.hasLength(this.patternString)) {
			if (!StringUtils.hasLength(pattern2string.patternString)) {
				return this.parser.parse("");
			}
			else {
				return pattern2string;
			}
		}
		else if (!StringUtils.hasLength(pattern2string.patternString)) {
			return this;
		}

		// /* + /hotel => /hotel
		// /*.* + /*.html => /*.html
		// However:
		// /usr + /user => /usr/user
		// /{foo} + /bar => /{foo}/bar
		if (!this.patternString.equals(pattern2string.patternString) && this.capturedVariableCount == 0 &&
				matches(PathContainer.parsePath(pattern2string.patternString))) {
			return pattern2string;
		}

		// /hotels/* + /booking => /hotels/booking
		// /hotels/* + booking => /hotels/booking
		if (this.endsWithSeparatorWildcard) {
			return this.parser.parse(concat(
					this.patternString.substring(0, this.patternString.length() - 2),
					pattern2string.patternString));
		}

		// /hotels + /booking => /hotels/booking
		// /hotels + booking => /hotels/booking
		int starDotPos1 = this.patternString.indexOf("*.");  // Are there any file prefix/suffix things to consider?
		if (this.capturedVariableCount != 0 || starDotPos1 == -1 || this.separator == '.') {
			return this.parser.parse(concat(this.patternString, pattern2string.patternString));
		}

		// /*.html + /hotel => /hotel.html
		// /*.html + /hotel.* => /hotel.html
		String firstExtension = this.patternString.substring(starDotPos1 + 1);  // looking for the first extension
		String p2string = pattern2string.patternString;
		int dotPos2 = p2string.indexOf('.');
		String file2 = (dotPos2 == -1 ? p2string : p2string.substring(0, dotPos2));
		String secondExtension = (dotPos2 == -1 ? "" : p2string.substring(dotPos2));
		boolean firstExtensionWild = (firstExtension.equals(".*") || firstExtension.equals(""));
		boolean secondExtensionWild = (secondExtension.equals(".*") || secondExtension.equals(""));
		if (!firstExtensionWild && !secondExtensionWild) {
			throw new IllegalArgumentException(
					"Cannot combine patterns: " + this.patternString + " and " + pattern2string);
		}
		return this.parser.parse(file2 + (firstExtensionWild ? secondExtension : firstExtension));
	}

	public boolean equals(Object other) {
		if (!(other instanceof PathPattern)) {
			return false;
		}
		PathPattern otherPattern = (PathPattern) other;
		return (this.patternString.equals(otherPattern.getPatternString()) &&
				this.separator == otherPattern.getSeparator() &&
				this.caseSensitive == otherPattern.caseSensitive);
	}

	public int hashCode() {
		return (this.patternString.hashCode() + this.separator) * 17 + (this.caseSensitive ? 1 : 0);
	}

	public String toString() {
		return this.patternString;
	}

	int getScore() {
		return this.score;
	}

	boolean isCatchAll() {
		return this.catchAll;
	}

	
The normalized length is trying to measure the 'active' part of the pattern. It is computed
by assuming all capture variables have a normalized length of 1. Effectively this means changing
your variable name lengths isn't going to change the length of the active part of the pattern.
Useful when comparing two patterns.
/**
	 * The normalized length is trying to measure the 'active' part of the pattern. It is computed
	 * by assuming all capture variables have a normalized length of 1. Effectively this means changing
	 * your variable name lengths isn't going to change the length of the active part of the pattern.
	 * Useful when comparing two patterns.
	 */
	int getNormalizedLength() {
		return this.normalizedLength;
	}

	char getSeparator() {
		return this.separator;
	}

	int getCapturedVariableCount() {
		return this.capturedVariableCount;
	}

	String toChainString() {
		StringBuilder buf = new StringBuilder();
		PathElement pe = this.head;
		while (pe != null) {
			buf.append(pe.toString()).append(" ");
			pe = pe.next;
		}
		return buf.toString().trim();
	}

	
Return the string form of the pattern built from walking the path element chain.
Returns:
the string form of the pattern/**
	 * Return the string form of the pattern built from walking the path element chain.
	 * @return the string form of the pattern
	 */
	String computePatternString() {
		StringBuilder buf = new StringBuilder();
		PathElement pe = this.head;
		while (pe != null) {
			buf.append(pe.getChars());
			pe = pe.next;
		}
		return buf.toString();
	}

	@Nullable
	PathElement getHeadSection() {
		return this.head;
	}

	
Join two paths together including a separator if necessary.
Extraneous separators are removed (if the first path
ends with one and the second path starts with one).
Params:
path1 – first path
path2 – second path
Returns:
joined path that may include separator if necessary/**
	 * Join two paths together including a separator if necessary.
	 * Extraneous separators are removed (if the first path
	 * ends with one and the second path starts with one).
	 * @param path1 first path
	 * @param path2 second path
	 * @return joined path that may include separator if necessary
	 */
	private String concat(String path1, String path2) {
		boolean path1EndsWithSeparator = (path1.charAt(path1.length() - 1) == this.separator);
		boolean path2StartsWithSeparator = (path2.charAt(0) == this.separator);
		if (path1EndsWithSeparator && path2StartsWithSeparator) {
			return path1 + path2.substring(1);
		}
		else if (path1EndsWithSeparator || path2StartsWithSeparator) {
			return path1 + path2;
		}
		else {
			return path1 + this.separator + path2;
		}
	}

	
Return if the container is not null and has more than zero elements.
Params:
container – a path container
Returns:
true has more than zero elements/**
	 * Return if the container is not null and has more than zero elements.
	 * @param container a path container
	 * @return {@code true} has more than zero elements
	 */
	private boolean hasLength(@Nullable PathContainer container) {
		return container != null && container.elements().size() > 0;
	}

	private static int scoreByNormalizedLength(PathPattern pattern) {
		return -pattern.getNormalizedLength();
	}

	private boolean pathContainerIsJustSeparator(PathContainer pathContainer) {
		return pathContainer.value().length() == 1 &&
				pathContainer.value().charAt(0) == this.separator;
	}

	
Holder for URI variables and path parameters (matrix variables) extracted
based on the pattern for a given matched path.
/**
	 * Holder for URI variables and path parameters (matrix variables) extracted
	 * based on the pattern for a given matched path.
	 */
	public static class PathMatchInfo {

		private static final PathMatchInfo EMPTY =
				new PathMatchInfo(Collections.emptyMap(), Collections.emptyMap());


		private final Map<String, String> uriVariables;

		private final Map<String, MultiValueMap<String, String>> matrixVariables;


		PathMatchInfo(Map<String, String> uriVars,
				@Nullable Map<String, MultiValueMap<String, String>> matrixVars) {

			this.uriVariables = Collections.unmodifiableMap(uriVars);
			this.matrixVariables = matrixVars != null ?
					Collections.unmodifiableMap(matrixVars) : Collections.emptyMap();
		}


		
Return the extracted URI variables.
/**
		 * Return the extracted URI variables.
		 */
		public Map<String, String> getUriVariables() {
			return this.uriVariables;
		}

		
Return maps of matrix variables per path segment, keyed off by URI
variable name.
/**
		 * Return maps of matrix variables per path segment, keyed off by URI
		 * variable name.
		 */
		public Map<String, MultiValueMap<String, String>> getMatrixVariables() {
			return this.matrixVariables;
		}

		@Override
		public String toString() {
			return "PathMatchInfo[uriVariables=" + this.uriVariables + ", " +
					"matrixVariables=" + this.matrixVariables + "]";
		}
	}


	
Holder for the result of a match on the start of a pattern.
Provides access to the remaining path not matched to the pattern as well
as any variables bound in that first part that was matched.
/**
	 * Holder for the result of a match on the start of a pattern.
	 * Provides access to the remaining path not matched to the pattern as well
	 * as any variables bound in that first part that was matched.
	 */
	public static class PathRemainingMatchInfo {

		private final PathContainer pathRemaining;

		private final PathMatchInfo pathMatchInfo;


		PathRemainingMatchInfo(PathContainer pathRemaining) {
			this(pathRemaining, PathMatchInfo.EMPTY);
		}

		PathRemainingMatchInfo(PathContainer pathRemaining, PathMatchInfo pathMatchInfo) {
			this.pathRemaining = pathRemaining;
			this.pathMatchInfo = pathMatchInfo;
		}

		
Return the part of a path that was not matched by a pattern.
/**
		 * Return the part of a path that was not matched by a pattern.
		 */
		public PathContainer getPathRemaining() {
			return this.pathRemaining;
		}

		
Return variables that were bound in the part of the path that was
successfully matched or an empty map.
/**
		 * Return variables that were bound in the part of the path that was
		 * successfully matched or an empty map.
		 */
		public Map<String, String> getUriVariables() {
			return this.pathMatchInfo.getUriVariables();
		}

		
Return the path parameters for each bound variable.
/**
		 * Return the path parameters for each bound variable.
		 */
		public Map<String, MultiValueMap<String, String>> getMatrixVariables() {
			return this.pathMatchInfo.getMatrixVariables();
		}
	}


	
Encapsulates context when attempting a match. Includes some fixed state like the
candidate currently being considered for a match but also some accumulators for
extracted variables.
/**
	 * Encapsulates context when attempting a match. Includes some fixed state like the
	 * candidate currently being considered for a match but also some accumulators for
	 * extracted variables.
	 */
	class MatchingContext {

		final PathContainer candidate;

		final List<Element> pathElements;

		final int pathLength;

		@Nullable
		private Map<String, String> extractedUriVariables;

		@Nullable
		private Map<String, MultiValueMap<String, String>> extractedMatrixVariables;

		boolean extractingVariables;

		boolean determineRemainingPath = false;

		// if determineRemaining is true, this is set to the position in
		// the candidate where the pattern finished matching - i.e. it
		// points to the remaining path that wasn't consumed
		int remainingPathIndex;

		public MatchingContext(PathContainer pathContainer, boolean extractVariables) {
			this.candidate = pathContainer;
			this.pathElements = pathContainer.elements();
			this.pathLength = this.pathElements.size();
			this.extractingVariables = extractVariables;
		}

		public void setMatchAllowExtraPath() {
			this.determineRemainingPath = true;
		}

		public boolean isMatchOptionalTrailingSeparator() {
			return matchOptionalTrailingSeparator;
		}

		public void set(String key, String value, MultiValueMap<String,String> parameters) {
			if (this.extractedUriVariables == null) {
				this.extractedUriVariables = new HashMap<>();
			}
			this.extractedUriVariables.put(key, value);

			if (!parameters.isEmpty()) {
				if (this.extractedMatrixVariables == null) {
					this.extractedMatrixVariables = new HashMap<>();
				}
				this.extractedMatrixVariables.put(key, CollectionUtils.unmodifiableMultiValueMap(parameters));
			}
		}

		public PathMatchInfo getPathMatchResult() {
			if (this.extractedUriVariables == null) {
				return PathMatchInfo.EMPTY;
			}
			else {
				return new PathMatchInfo(this.extractedUriVariables, this.extractedMatrixVariables);
			}
		}

		
Return if element at specified index is a separator.
Params:
pathIndex – possible index of a separator
Returns:
true if element is a separator/**
		 * Return if element at specified index is a separator.
		 * @param pathIndex possible index of a separator
		 * @return {@code true} if element is a separator
		 */
		boolean isSeparator(int pathIndex) {
			return this.pathElements.get(pathIndex) instanceof Separator;
		}

		
Return the decoded value of the specified element.
Params:
pathIndex – path element index
Returns:
the decoded value/**
		 * Return the decoded value of the specified element.
		 * @param pathIndex path element index
		 * @return the decoded value
		 */
		String pathElementValue(int pathIndex) {
			Element element = (pathIndex < this.pathLength) ? this.pathElements.get(pathIndex) : null;
			if (element instanceof PathContainer.PathSegment) {
				return ((PathContainer.PathSegment)element).valueToMatch();
			}
			return "";
		}
	}
}