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LESS compiler in Java based on less.js
/**
* Copyright (c) 2014 SQUARESPACE, 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.
*/
package com.squarespace.less.exec;
import static com.squarespace.less.core.ExecuteErrorMaker.argCount;
import static com.squarespace.less.core.ExecuteErrorMaker.invalidArg;
import static com.squarespace.less.model.NodeType.COLOR;
import static com.squarespace.less.model.NodeType.DIMENSION;
import static com.squarespace.less.model.NodeType.KEYWORD;
import static com.squarespace.less.model.NodeType.QUOTED;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import com.squarespace.less.LessErrorInfo;
import com.squarespace.less.LessException;
import com.squarespace.less.LessOptions;
import com.squarespace.less.model.Argument;
import com.squarespace.less.model.Dimension;
import com.squarespace.less.model.FunctionCall;
import com.squarespace.less.model.Node;
import com.squarespace.less.model.NodeType;
import com.squarespace.less.model.Unit;
/**
* Defines a {@link FunctionCall}'s signature.
*/
public class ArgSpec {
/**
* Validate the arguments before invoking a function.
*/
private final List validators;
/**
* Minimum number of arguments required.
*/
private final int minArgs;
/**
* Whether the function accepts a variable number of arguments.
*/
private final boolean variadic;
/**
* Constructs an instance which ensures that the arguments are of the
* given {@code types}.
*/
public ArgSpec(NodeType ... types) {
this(types.length, types);
}
/**
* Like {@link ArgSpec#ArgSpec(NodeType...)} but ensures that at least
* {@code minArgs} are passed.
*/
public ArgSpec(int minArgs, NodeType ... types) {
this(minArgs, build(types));
}
/**
* Constructs an instance which ensures that the arguments are valid,
* using the given {@code validators}. Each {@link ArgValidator}
* validates the argument in the corresponding position.
*/
public ArgSpec(ArgValidator ... validators) {
this(validators.length, validators);
}
/**
* Like {@link ArgSpec#ArgSpec(ArgValidator...)} but ensures that at least
* {@code minArgs} are passed.
*/
public ArgSpec(int minArgs, ArgValidator ... validators) {
this(minArgs, Arrays.asList(validators), false);
}
/**
* Like {@link ArgSpec#ArgSpec(int, ArgValidator...)} with variable argument
* support.
*/
public ArgSpec(int minArgs, List validators, boolean variadic) {
if (!variadic && validators.size() < minArgs) {
throw new IllegalArgumentException("minArgs cannot be < zero or exceed types.length");
}
this.minArgs = minArgs;
this.validators = validators;
this.variadic = variadic;
}
/**
* Builds validators which ensure that the arguments are of the given {@code types}.
*/
private static ArgValidator[] build(NodeType ... types) {
return build(Arrays.asList(types));
}
/**
* Builds validators which ensure that the arguments are of the given {@code types}.
*/
private static ArgValidator[] build(List types) {
int size = types.size();
ArgValidator[] validators = new ArgValidator[size];
for (int i = 0; i < size; i++) {
validators[i] = new ArgTypeValidator(types.get(i));
}
return validators;
}
/**
* Validates the arguments.
*/
public boolean validate(ExecEnv env, Function func, Node ... args) throws LessException {
return validate(env, func, Arrays.asList(args));
}
/**
* Validates the arguments.
*/
public boolean validate(ExecEnv env, Function func, List args) throws LessException {
int size = args.size();
if (size < minArgs) {
throw new LessException(argCount(func.name(), minArgs, size));
} else if (size > validators.size() && !variadic) {
LessOptions opts = env.context().options();
LessErrorInfo info = argCount(func.name(), minArgs, size);
if (opts.strict()) {
throw new LessException(info);
}
if (!opts.hideWarnings()) {
// Ignore the additional arguments.
env.addWarning(info.getMessage() + ".. ignoring additional args");
}
size = validators.size();
}
if (variadic) {
size = validators.size();
}
for (int i = 0; i < size; i++) {
validators.get(i).validate(i, args.get(i));
}
return true;
}
/**
* Parses the specification string into an {@link ArgSpec} instance.
*/
public static ArgSpec fromString(String raw) {
List validators = new ArrayList<>();
int minArgs = -1;
int size = raw.length();
boolean variadic = false;
for (int i = 0; i < size; i++) {
char ch = raw.charAt(i);
switch (ch) {
case 'p':
validators.add(ARG_PERCENTAGE);
break;
case 'n':
validators.add(ARG_NUMBER);
break;
case '*':
validators.add(ARG_ANY);
break;
case ':':
minArgs = i;
break;
case '.':
variadic = true;
minArgs = i;
break;
default:
validators.add(new ArgTypeValidator(fromChar(ch)));
break;
}
if (variadic) {
break;
}
}
if (minArgs == -1) {
minArgs = size;
}
return new ArgSpec(minArgs, validators, variadic);
}
/**
* Maps the specification character to a node type.
*/
private static NodeType fromChar(char ch) {
switch (ch) {
case 'c':
return COLOR;
case 'd':
return DIMENSION;
case 'k':
return KEYWORD;
case 's':
return QUOTED;
default:
break;
}
throw new IllegalArgumentException("Unknown type ch: '" + ch + "'");
}
/**
* Validates an {@link Argument} by its {@link Node#type()}.
*/
static class ArgTypeValidator extends ArgValidator {
private final NodeType type;
ArgTypeValidator(NodeType type) {
this.type = type;
}
@Override
public void validate(int index, Node arg) throws LessException {
if (arg.type() != type) {
throw new LessException(invalidArg(index + 1, type, arg.type()));
}
}
}
/**
* Validator which accepts any node type.
*/
private static final ArgValidator ARG_ANY = new ArgValidator() {
@Override
public void validate(int index, Node arg) throws LessException {
// any node type is valid.
};
};
/**
* Validator which only accepts a unit-less number.
*/
private static final ArgValidator ARG_NUMBER = new ArgValidator() {
@Override
public void validate(int index, Node arg) throws LessException {
if (arg.type() != DIMENSION) {
throw new LessException(invalidArg(index + 1, DIMENSION, arg.type()));
}
Dimension dim = (Dimension)arg;
if (dim.unit() == null) {
return;
}
throw new LessException(invalidArg(index, "a unit-less number", arg.type()));
}
};
/**
* Validator which only accepts numbers in percentage units.
*/
private static final ArgValidator ARG_PERCENTAGE = new ArgValidator() {
@Override
public void validate(int index, Node arg) throws LessException {
if (arg.type() != DIMENSION) {
throw new LessException(invalidArg(index + 1, DIMENSION, arg.type()));
}
Dimension dim = (Dimension)arg;
if (dim.unit() == null || dim.unit() == Unit.PERCENTAGE) {
return;
}
throw new LessException(invalidArg(index + 1, "a unit-less number or a percentage", arg.type()));
}
};
}
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