Expression.java
/*
* Copyright 2012, Ryan J. McDonough
*
* 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 com.damnhandy.uri.template;
import com.damnhandy.uri.template.impl.Modifier;
import com.damnhandy.uri.template.impl.Operator;
import com.damnhandy.uri.template.impl.VarSpec;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* <p>
* An Expression represents the text between '{' and '}', including the enclosing
* braces, as defined in <a href="ietf.org/html/rfc6570#section-2">Section 2 of RFC6570</a>.
* </p>
* <pre>
* http://www.example.com/foo{?query,number}
* \___________/
* ^
* |
* |
* The expression
* </pre>
* <p>
* This class models this representation and adds helper functions for replacement and reverse matching.
* </p>
*
* @author <a href="ryan@damnhandy.com">Ryan J. McDonough</a>
* @version $Revision: 1.1 $
* @since 2.0
*/
public class Expression extends UriTemplateComponent
{
/**
* The serialVersionUID
*/
private static final long serialVersionUID = -5305648325957481840L;
/**
* A regex quoted string that matches the expression for replacement in the
* expansion process. For example:
* <pre>
* \Q{?query,number}\E
* </pre>
*/
private String replacementPattern;
/**
* That {@link Operator} value that is associated with this Expression
*/
private Operator op;
/**
* The character position where this expression occurs in the URI template
*/
private final int location;
/**
* The the parsed {@link VarSpec} instances found in the expression.
*/
private List<VarSpec> varSpecs;
/**
* The Patter that would be used to reverse match this expression
*/
private Pattern matchPattern;
/**
* Creates a new {@link Builder} to create a simple expression according
* to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.2">3.2.2</a>.
* Calling:
* <pre>
* String exp = Expression.simple(var("var")).build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {var}
* </pre>
*
* @return
*/
public static Builder simple(VarSpec... varSpec)
{
return Builder.create(Operator.NUL, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression that will use reserved expansion
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.3">3.2.3</a>.
* Calling:
* <pre>
* String exp = Expression.reserved().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {+var}
* </pre>
*
* @return
*/
public static Builder reserved(VarSpec... varSpec)
{
return Builder.create(Operator.RESERVED, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression with a fragment operator
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.4">3.2.4</a>.
* Calling:
* <pre>
* String exp = Expression.fragment().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {#var}
* </pre>
*
* @return
*/
public static Builder fragment(VarSpec... varSpec)
{
return Builder.create(Operator.FRAGMENT, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression using label expansion
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.5">3.2.5</a>.
* Calling:
* <pre>
* String exp = Expression.label(var("var")).build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {.var}
* </pre>
*
* @return
*/
public static Builder label(VarSpec... varSpec)
{
return Builder.create(Operator.NAME_LABEL, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression using path expansion
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.6">3.2.6</a>.
* Calling:
* <pre>
* String exp = Expression.path().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {/var}
* </pre>
*
* @return
*/
public static Builder path(VarSpec... varSpec)
{
return Builder.create(Operator.PATH, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression using path-style parameter
* (a.k.a. matrix parameter) expansion according to
* section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.7">3.2.7</a>.
* Calling:
* <pre>
* String exp = Expression.matrix().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {;var}
* </pre>
*
* @return the builder
*/
public static Builder matrix(VarSpec... varSpec)
{
return Builder.create(Operator.MATRIX, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression using form-style query string expansion
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.8">3.2.8</a>.
* Calling:
* <pre>
* String exp = Expression.query().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {?var}
* </pre>
*
* @return
*/
public static Builder query(VarSpec... varSpec)
{
return Builder.create(Operator.QUERY, varSpec);
}
/**
* Creates a new {@link Builder} to create an expression using form-style query continuation expansion
* according to section <a href="http://tools.ietf.org/html/rfc6570#section-3.2.9">3.2.9</a>.
* Calling:
* <pre>
* String exp = Expression.continuation().var("var").build().toString();
* </pre>
* <p>
* Will return the following expression:
* </p>
* <pre>
* {&var}
* </pre>
*
* @return
*/
public static Builder continuation(VarSpec... varSpec)
{
return Builder.create(Operator.CONTINUATION, varSpec);
}
/**
* Create a new Expression.
*
* @param rawExpression
* @param startPosition
* @throws MalformedUriTemplateException
*/
public Expression(final String rawExpression, final int startPosition) throws MalformedUriTemplateException
{
super(startPosition);
this.location = startPosition;
this.parseRawExpression(rawExpression);
}
/**
* Create a new Expression
*
* @param op
* @param varSpecs
* @throws MalformedUriTemplateException
*/
public Expression(final Operator op, final List<VarSpec> varSpecs)
{
super(0);
this.op = op;
this.varSpecs = varSpecs;
this.replacementPattern = Pattern.quote(toString());
this.location = 0;
}
/**
* @param rawExpression
* @throws MalformedUriTemplateException
*/
private void parseRawExpression(String rawExpression) throws MalformedUriTemplateException
{
final String expressionReplacement = Pattern.quote(rawExpression);
String token = rawExpression.substring(1, rawExpression.length() - 1);
// Check for URI operators
Operator operator = Operator.NUL;
String firstChar = token.substring(0, 1);
if (UriTemplate.containsOperator(firstChar))
{
try
{
operator = Operator.fromOpCode(firstChar);
}
catch (IllegalArgumentException e)
{
throw new MalformedUriTemplateException("Invalid operator", this.location, e);
}
token = token.substring(1, token.length());
}
String[] varspecStrings = token.split(",");
List<VarSpec> varspecs = new ArrayList<VarSpec>();
for (String varname : varspecStrings)
{
int subStrPos = varname.indexOf(Modifier.PREFIX.getValue());
/*
* Prefix variable
*/
if (subStrPos > 0)
{
String[] pair = varname.split(Modifier.PREFIX.getValue());
try
{
Integer pos = Integer.valueOf(varname.substring(subStrPos + 1));
varspecs.add(new VarSpec(pair[0], Modifier.PREFIX, pos));
}
catch (NumberFormatException e)
{
throw new MalformedUriTemplateException("The prefix value for " + pair[0] + " was not a number", this.location, e);
}
}
/*
* Variable will be exploded
*/
else if (varname.lastIndexOf(Modifier.EXPLODE.getValue()) > 0)
{
varspecs.add(new VarSpec(varname, Modifier.EXPLODE));
}
/*
* Standard Value
*/
else
{
varspecs.add(new VarSpec(varname, Modifier.NONE));
}
}
this.replacementPattern = expressionReplacement;
this.op = operator;
this.varSpecs = varspecs;
}
private Pattern buildMatchingPattern()
{
StringBuilder b = new StringBuilder();
for (VarSpec v : getVarSpecs())
{
b.append("(?<").append(v.getVariableName()).append(">[^\\/]+)");
}
return Pattern.compile(b.toString());
}
/**
* Returns a string that contains a regular expression that matches the
* URI template expression.
*
* @return the match pattern
*/
@Override
public Pattern getMatchPattern()
{
if (this.matchPattern == null)
{
this.matchPattern = buildMatchingPattern();
}
return this.matchPattern;
}
/**
* Get the replacementToken.
*
* @return the replacementToken.
*/
public String getReplacementPattern()
{
return replacementPattern;
}
/**
* Get the {@link Operator} value for this expression.
*
* @return the operator value.
*/
public Operator getOperator()
{
return op;
}
/**
* Get the varSpecs.
*
* @return the varSpecs.
*/
public List<VarSpec> getVarSpecs()
{
return varSpecs;
}
/**
* Returns the string representation of the expression.
*
* @see Object#toString()
*/
public String toString()
{
StringBuilder b = new StringBuilder();
b.append("{").append(this.getOperator().getOperator());
for (int i = 0; i < varSpecs.size(); i++)
{
VarSpec v = varSpecs.get(i);
b.append(v.getValue());
// Double check that the value doesn't already contain the modifier
int r = v.getValue().lastIndexOf(v.getModifier().getValue());
if(v.getModifier() != null && v.getValue().lastIndexOf(v.getModifier().getValue()) == -1)
{
b.append(v.getModifier().getValue());
}
if (v.getModifier() == Modifier.PREFIX)
{
b.append(v.getPosition());
}
if (i != (varSpecs.size() - 1))
{
b.append(",");
}
}
return b.append("}").toString();
}
/**
* Returns the value of this component
*
* @return the string value of this component.
*/
@Override
public String getValue()
{
return toString();
}
@Override
public int hashCode()
{
final int prime = 31;
int result = 1;
result = prime * result + ((op == null) ? 0 : op.hashCode());
result = prime * result + ((varSpecs == null) ? 0 : varSpecs.hashCode());
return result;
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
{
return true;
}
if (obj == null)
{
return false;
}
if (getClass() != obj.getClass())
{
return false;
}
Expression other = (Expression) obj;
if (op != other.op)
{
return false;
}
if (varSpecs == null)
{
if (other.varSpecs != null)
{
return false;
}
}
else if (!varSpecs.equals(other.varSpecs))
{
return false;
}
return true;
}
/**
* Builder class for creating an {@link Expression}.
*
* @author <a href="ryan@damnhandy.com">Ryan J. McDonough</a>
* @version $Revision: 1.1 $
*/
public static class Builder
{
/**
*
*/
private Operator operator;
/**
*
*/
private List<VarSpec> varSpecs;
/**
* Create a new ExpressionBuilder.
*
* @param operator
*/
private Builder(Operator operator, VarSpec... varSpec)
{
this.operator = operator;
this.varSpecs = new ArrayList<VarSpec>();
for (VarSpec v : varSpec)
{
varSpecs.add(v);
}
}
/**
* @param operator
* @return the builder
*/
static Builder create(Operator operator, VarSpec... varSpec)
{
return new Builder(operator, varSpec);
}
public Expression build()
{
return new Expression(operator, varSpecs);
}
}
}