CLParser.java

/*
 * Copyright (C) 2021 The Android Open Source Project
 *
 * 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 androidx.constraintlayout.core.parser;

public class CLParser {

  static boolean DEBUG = false;

  private String mContent;
  private boolean hasComment = false;
  private int lineNumber;

  enum TYPE {UNKNOWN, OBJECT, ARRAY, NUMBER, STRING, KEY, TOKEN}

  public static CLObject parse(String string) throws CLParsingException {
    return (new CLParser(string)).parse();
  }

  public CLParser(String content) {
    mContent = content;
  }

  public CLObject parse() throws CLParsingException {
    CLObject root = null;

    char[] content = mContent.toCharArray();
    CLElement currentElement = null;

    final int length = content.length;

    // First, let's find the root element start
    lineNumber = 1;

    int startIndex = -1;
    for (int i = 0; i < length; i++) {
      char c = content[i];
      if (c == '{') {
        startIndex = i;
        break;
      }
      if (c == '\n') {
        lineNumber++;
      }
    }
    if (startIndex == -1) {
      throw new CLParsingException("invalid json content", null);
    }

    // We have a root object, let's start
    root = CLObject.allocate(content);
    root.setLine(lineNumber);
    root.setStart(startIndex);
    currentElement = root;

    for (int i = startIndex + 1; i < length; i++) {
      char c = content[i];
      if (c == '\n') {
        lineNumber++;
      }
      if (hasComment) {
        if (c == '\n') {
          hasComment = false;
        } else {
          continue;
        }
      }
      if (false) {
        System.out.println("Looking at " + i + " : <" + c + ">");
      }
      if (currentElement == null) {
        break;
      }
      if (currentElement.isDone()) {
        currentElement = getNextJsonElement(i, c, currentElement, content);
      } else if (currentElement instanceof CLObject) {
        if (c == '}') {
          currentElement.setEnd(i - 1);
        } else {
          currentElement = getNextJsonElement(i, c, currentElement, content);
        }
      } else if (currentElement instanceof CLArray) {
        if (c == ']') {
          currentElement.setEnd(i - 1);
        } else {
          currentElement = getNextJsonElement(i, c, currentElement, content);
        }
      } else if (currentElement instanceof CLString) {
        char ck = content[(int) currentElement.start];
        if (ck == c) {
          currentElement.setStart(currentElement.start + 1);
          currentElement.setEnd(i - 1);
        }
      } else {
        if (currentElement instanceof CLToken) {
          CLToken token = (CLToken) currentElement;
          if (!token.validate(c, i)) {
            throw new CLParsingException("parsing incorrect token " + token.content() +
                    " at line " + lineNumber, token);
          }
        }
        if (currentElement instanceof CLKey || currentElement instanceof CLString) {
          char ck = content[(int) currentElement.start];
          if ((ck == '


' || ck == '"') && ck == c) { currentElement.setStart(currentElement.start + 1); currentElement.setEnd(i - 1); } } if (!currentElement.isDone()) { if (c == '}' || c == ']' || c == ',' || c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == ':') { currentElement.setEnd(i - 1); if (c == '}' || c == ']') { currentElement = currentElement.getContainer(); currentElement.setEnd(i - 1); if (currentElement instanceof CLKey) { currentElement = currentElement.getContainer(); currentElement.setEnd(i - 1); } } } } } if (currentElement.isDone() && (!(currentElement instanceof CLKey) || ((CLKey) currentElement).mElements.size() > 0) ) { currentElement = currentElement.getContainer(); } } // Close all open elements -- allow us to be more resistant to invalid json, useful during editing. while (currentElement != null && !currentElement.isDone()) { if (currentElement instanceof CLString) { currentElement.setStart((int) currentElement.start + 1); } currentElement.setEnd(length - 1); currentElement = currentElement.getContainer(); } if (DEBUG) { System.out.println("Root: " + root.toJSON()); } return root; } private CLElement getNextJsonElement(int position, char c, CLElement currentElement, char[] content) throws CLParsingException { switch (c) { case ' ': case ':': case ',': case '\t': case '\r': case '\n': { // skip space } break; case '{': { currentElement = createElement(currentElement, position, TYPE.OBJECT, true, content); } break; case '[': { currentElement = createElement(currentElement, position, TYPE.ARRAY, true, content); } break; case ']': case '}': { currentElement.setEnd(position-1); currentElement = currentElement.getContainer(); currentElement.setEnd(position); } break; case '"': case '

'
: { if (currentElement instanceof CLObject) { currentElement = createElement(currentElement, position, TYPE.KEY, true, content); } else { currentElement = createElement(currentElement, position, TYPE.STRING, true, content); } } break; case '/': { if (position + 1 < content.length && content[position + 1] == '/') { hasComment = true; } } break; case '-': case '+': case '.': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': { currentElement = createElement(currentElement, position, TYPE.NUMBER, true, content); } break; default: { if (currentElement instanceof CLContainer && !(currentElement instanceof CLObject)) { currentElement = createElement(currentElement, position, TYPE.TOKEN, true, content); CLToken token = (CLToken) currentElement; if (!token.validate(c, position)) { throw new CLParsingException("incorrect token <" + c + "> at line " + lineNumber, token); } } else { currentElement = createElement(currentElement, position, TYPE.KEY, true, content); } } } return currentElement; } private CLElement createElement(CLElement currentElement, int position, TYPE type, boolean applyStart, char[] content) { CLElement newElement = null; if (DEBUG) { System.out.println("CREATE " + type + " at " + content[position]); } switch (type) { case OBJECT: { newElement = CLObject.allocate(content); position++; } break; case ARRAY: { newElement = CLArray.allocate(content); position++; } break; case STRING: { newElement = CLString.allocate(content); } break; case NUMBER: { newElement = CLNumber.allocate(content); } break; case KEY: { newElement = CLKey.allocate(content); } break; case TOKEN: { newElement = CLToken.allocate(content); } break; default: break; } if (newElement == null) { return null; } newElement.setLine(lineNumber); if (applyStart) { newElement.setStart(position); } if (currentElement instanceof CLContainer) { CLContainer container = (CLContainer) currentElement; newElement.setContainer(container); } return newElement; } }