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 sDebug = false;

    private String mContent;
    private boolean mHasComment = false;
    private int mLineNumber;

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

    // @TODO: add description
    public static CLObject parse(String string) throws CLParsingException {
        return new CLParser(string).parse();
    }

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

    // @TODO: add description
    public CLObject parse() throws CLParsingException {
        @SuppressWarnings("unused") CLObject root = null;

        char[] content = mContent.toCharArray();
        @SuppressWarnings("unused") CLElement currentElement = null;

        final int length = content.length;

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

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

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

        for (int i = startIndex + 1; i < length; i++) {
            char c = content[i];
            if (c == '\n') {
                mLineNumber++;
            }
            if (mHasComment) {
                if (c == '\n') {
                    mHasComment = 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.mStart];
                if (ck == c) {
                    currentElement.setStart(currentElement.mStart + 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 " + mLineNumber, token);
                    }
                }
                if (currentElement instanceof CLKey || currentElement instanceof CLString) {
                    char ck = content[(int) currentElement.mStart];
                    if ((ck == '


' || ck == '"') && ck == c) { currentElement.setStart(currentElement.mStart + 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.mStart + 1); } currentElement.setEnd(length - 1); currentElement = currentElement.getContainer(); } if (sDebug) { 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] == '/') { mHasComment = 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 " + mLineNumber, 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 (sDebug) { 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(mLineNumber); if (applyStart) { newElement.setStart(position); } if (currentElement instanceof CLContainer) { CLContainer container = (CLContainer) currentElement; newElement.setContainer(container); } return newElement; } }