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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.model;
import static com.squarespace.less.core.LessUtils.safeEquals;
import static com.squarespace.less.model.Operator.EQUAL;
import static com.squarespace.less.model.Operator.GREATER_THAN;
import static com.squarespace.less.model.Operator.GREATER_THAN_OR_EQUAL;
import static com.squarespace.less.model.Operator.LESS_THAN;
import static com.squarespace.less.model.Operator.LESS_THAN_OR_EQUAL;
import static com.squarespace.less.model.Operator.NOT_EQUAL;
import com.squarespace.less.LessException;
import com.squarespace.less.core.Buffer;
import com.squarespace.less.core.Constants;
import com.squarespace.less.core.ExecuteErrorMaker;
import com.squarespace.less.core.LessInternalException;
import com.squarespace.less.exec.ExecEnv;
/**
* Represents one conditional clause in a {@link Guard}.
*/
public class Condition extends BaseNode {
/**
* Operator to apply to the left and right operands.
*/
protected final Operator operator;
/**
* Left operand.
*/
protected final Node left;
/**
* Right operand.
*/
protected final Node right;
/**
* Whether to negate the result of the evaluation.
*/
protected final boolean negate;
/**
* Constructs a conditional clause, applying the boolean operator to the left
* and right operands. Negates the result if the {@code negate} flag is set.
*/
public Condition(Operator operator, Node left, Node right, boolean negate) {
if (operator == null || left == null || right == null) {
throw new LessInternalException("Serious error: operator/operands cannot be null.");
}
this.operator = operator;
this.left = left;
this.right = right;
this.negate = negate;
}
/**
* Returns the left operand.
*/
public Node left() {
return left;
}
/**
* Returns the right operand.
*/
public Node right() {
return right;
}
/**
* See {@link Node#needsEval()}
*/
@Override
public boolean needsEval() {
return true;
}
/**
* See {@link Node#eval(ExecEnv)}
*/
@Override
public Node eval(ExecEnv env) throws LessException {
boolean result = negate ? !compare(env) : compare(env);
return result ? Constants.TRUE : Constants.FALSE;
}
/**
* See {@link Node#type()}
*/
@Override
public NodeType type() {
return NodeType.CONDITION;
}
/**
* See {@link Node#repr()}
*/
@Override
public void repr(Buffer buf) {
if (negate) {
buf.append("not ");
}
boolean nested = (left instanceof Condition) || (right instanceof Condition);
if (!nested) {
buf.append('(');
}
left.repr(buf);
buf.append(' ').append(operator.toString()).append(' ');
right.repr(buf);
if (!nested) {
buf.append(')');
}
}
/**
* See {@link Node#modelRepr(Buffer)}
*/
@Override
public void modelRepr(Buffer buf) {
typeRepr(buf);
posRepr(buf);
buf.append(' ').append(operator.toString());
if (negate) {
buf.append(" [negate]");
}
buf.append('\n').incrIndent().indent();
left.modelRepr(buf);
buf.append('\n').indent();
right.modelRepr(buf);
buf.append('\n').decrIndent();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Condition) {
Condition other = (Condition)obj;
boolean res = operator == other.operator
&& negate == other.negate
&& safeEquals(left, other.left)
&& safeEquals(right, other.right);
return res;
}
return false;
}
@Override
public int hashCode() {
return super.hashCode();
}
/**
* Executes the comparison of the operands.
*/
private boolean compare(ExecEnv env) throws LessException {
Node op0 = left.needsEval() ? left.eval(env) : left;
Node op1 = right.needsEval() ? right.eval(env) : right;
switch (operator) {
case ADD:
case DIVIDE:
case MULTIPLY:
case SUBTRACT:
throw new LessException(ExecuteErrorMaker.expectedBoolOp(operator));
case AND:
return conjunction(env, op0, op1);
case OR:
return disjunction(env, op0, op1);
default:
break;
}
NodeType type = op0.type();
int result = -1;
switch (type) {
case ANONYMOUS:
result = compare(env, (Anonymous)op0, op1);
break;
case COLOR:
result = compare((BaseColor)op0, op1);
break;
case DIMENSION:
result = compare((Dimension)op0, op1);
break;
case KEYWORD:
case TRUE:
case FALSE:
result = compare((Keyword)op0, op1);
break;
case QUOTED:
result = compare(env, (Quoted)op0, op1);
break;
default:
throw new LessException(ExecuteErrorMaker.uncomparableType(type));
}
switch (result) {
case -1:
return operator == LESS_THAN || operator == LESS_THAN_OR_EQUAL || operator == NOT_EQUAL;
case 0:
return operator == EQUAL || operator == LESS_THAN_OR_EQUAL || operator == GREATER_THAN_OR_EQUAL;
case 1:
return operator == GREATER_THAN || operator == GREATER_THAN_OR_EQUAL || operator == NOT_EQUAL;
default:
throw new LessInternalException("Serious error: comparison functions must return -1, 0, or 1. Got " + result);
}
}
/**
* Logical AND of the two operands.
*/
private boolean conjunction(ExecEnv env, Node left, Node right) throws LessException {
return truthValue(env, left) && truthValue(env, right);
}
/**
* Logical OR of the two operands.
*/
private boolean disjunction(ExecEnv env, Node left, Node right) throws LessException {
return truthValue(env, left) || truthValue(env, right);
}
/**
* Compares an {@link Anonymous} node to another node.
*/
private int compare(ExecEnv env, Anonymous anon, Node arg) throws LessException {
String value = env.context().render(arg);
return anon.value().compareTo(value);
}
/**
* Maps node types to a truth value based on LESS notion of "truthiness".
*/
private boolean truthValue(ExecEnv env, Node node) throws LessException {
switch (node.type()) {
case ANONYMOUS:
case KEYWORD:
case QUOTED:
return "true".equals(render(env, node));
case TRUE:
return true;
default:
return false;
}
}
/**
* Compares a {@link BaseColor} to another node.
*/
private int compare(BaseColor color, Node arg) throws LessException {
if (arg instanceof Keyword) {
Keyword kwd = (Keyword)arg;
RGBColor tmp = RGBColor.fromName(kwd.value());
if (tmp != null) {
arg = tmp;
}
}
if (!(arg instanceof BaseColor)) {
return -1;
}
RGBColor color0 = color.toRGB();
RGBColor color1 = ((BaseColor)arg).toRGB();
return color0.red() == color1.red()
&& color0.green() == color1.green()
&& color0.blue() == color1.blue()
&& color0.alpha() == color1.alpha() ? 0 : -1;
}
/**
* Compares a {@link Dimension} to another node.
*/
private int compare(Dimension dim0, Node arg) throws LessException {
if (arg instanceof Dimension) {
Dimension dim1 = (Dimension)arg;
double value0 = dim0.value();
Unit unit0 = dim0.unit();
Unit unit1 = dim1.unit();
unit0 = (unit0 == Unit.PERCENTAGE ? null : unit0);
unit1 = (unit1 == Unit.PERCENTAGE ? null : unit1);
double factor = 1.0;
double scaled = dim1.value();
if (dim0.unit() != dim1.unit()) {
factor = UnitConversions.factor(unit1, unit0);
if (factor == 0.0) {
return -1;
}
scaled *= factor;
}
return value0 < scaled ? -1 : (value0 > scaled ? 1 : 0);
}
return -1;
}
/**
* Compares a {@link Keyword} to another node.
*/
private int compare(Keyword keyword, Node arg) throws LessException {
if (arg instanceof Keyword) {
return compareTo(keyword.value(), ((Keyword)arg).value());
}
return -1;
}
/**
* Compares a {@link Quoted} to another node.
*/
private int compare(ExecEnv env, Quoted quoted, Node arg) throws LessException {
return compareTo(render(env, quoted), render(env, arg));
}
/**
* Renders a node to get its string representation, for comparison purposes.
*/
private String render(ExecEnv env, Node arg) throws LessException {
if (arg instanceof Anonymous) {
return ((Anonymous)arg).value();
} else if (arg instanceof Keyword) {
return ((Keyword)arg).value();
}
return env.context().render(arg);
}
/**
* Compares two strings.
*/
private int compareTo(String left, String right) {
int res = left.compareTo(right);
return res < 0 ? -1 : (res > 0) ? 1 : 0;
}
}
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