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LESS compiler in Java based on less.js

There is a newer version: 1.7.2

/**
 * 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 com.squarespace.less.LessException;
import com.squarespace.less.core.Buffer;
import com.squarespace.less.exec.ExecEnv;


/**
 * Methods common to all nodes.
 */
public interface Node {

  /**
   * The enumerated type of this node.
   */
  NodeType type();

  /**
   * Line offset from start of the file for this node's definition.
   */
  int lineOffset();

  /**
   * Character offset for the current line for this node's definition.
   */
  int charOffset();

  /**
   * Sets the line offset. Typically this will only used by the parser.
   */
  void setLineOffset(int offset);

  /**
   * Sets the character offset. Typically this will only be used by the parser.
   */
  void setCharOffset(int offset);

  /**
   * Returns the opaque object associated with this node.
   */
  Object userData();

  /**
   * Associates an opaque object with this node.
   */
  void userData(Object obj);

  /**
   * Returns the original LESS representation of this node as a string.
   */
  String repr();

  /**
   * Writes the original LESS representation of this node to the given {@link Buffer}.
   */
  void repr(Buffer buf);

  /**
   * Outputs a human-readable representation of the model node.
   */
  void modelRepr(Buffer buf);

  /**
   * Evaluates the node against the Frame and returns itself or a new Node
   * that is itself an Atom, e.g. reduced to its simplest form possible.
   */
  Node eval(ExecEnv env) throws LessException;

  /**
   * Optimization to avoid eval() when the node is an Atom or a composite
   * that contains no variable references.
   */
  boolean needsEval();

  /**
   * Called when a node participates on an operation.
   */
  Node operate(ExecEnv env, Operator op, Node arg) throws LessException;

}