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/* * Copyright 2011 vvakame <vvakame@gmail.com> */*from w w w . ja v a 2 s . c o m*/ * 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 net.vvakame.util.jsonpullparser; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Reader; import java.io.StringReader; import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.nio.charset.UnsupportedCharsetException; import java.util.ArrayList; import java.util.List; /** * A JSON pull parser implementation.<br> * The parser guarantees format correctness till the point it stands at any given moment.<br> * (however, a successful parse doesn't guarantee for overall concreteness of the document.)<br> * As it throws an exception anytime it encounters an unexpected format defect, it is imperative that the caller handles that situation gracefully. * * @author vvakame * */ public class JsonPullParser { /** * The token in the hand. * * @author vvakame */ public static enum State { /** * The initial state. */ ORIGIN, /** * Key.<br> * (e.g. {"key":...}) */ KEY, /** * String value.<br> * (e.g. {...:"value"}) */ VALUE_STRING, /** * * Long value.<br> * (e.g. {...:0123}) */ VALUE_LONG, /** * Double precision real value.<br> * (e.g. {...:0123.11}) */ VALUE_DOUBLE, /** * Boolean value.<br> * (e.g. {...:true}) */ VALUE_BOOLEAN, /** * The null value.<br> * (e.g. {...:null}) */ VALUE_NULL, /** * Hash start marker.<br> * (i.e. {) */ START_HASH, /** * Hash end marker.<br> * (e.g. }) */ END_HASH, /** * Array start marker.<br> * (e.g. [) */ START_ARRAY, /** * Array end marker.<br> * (e.g. ]) */ END_ARRAY, } /** * The fallback encoding for naive streams. */ public static final String DEFAULT_CHARSET_NAME = "UTF-8"; /** * The fallback encoding if naive streams. */ public static final Charset DEFAULT_CHARSET = Charset.forName(DEFAULT_CHARSET_NAME); BufferedReader br; final Stack<State> stack = new Stack<State>(); // ?????? State current; String valueStr; long valueLong; double valueDouble; boolean valueBoolean; State lookAhead = null; // ?????? boolean logEnabled = false; List<JsonSlice> slices = null; /** * Creates a new parser, using the given InputStream as its {@code JSON} feed. * * <p> * Assumes the characters in the stream are encoded in {@link #DEFAULT_CHARSET_NAME}. * </p> * * @param is * An InputStream serves as {@code JSON} feed (should be in the default encoding.) Cannot be null. * * @return {@link JsonPullParser} * @throws IllegalArgumentException * {@code null} has been passed in where not applicable. */ public static JsonPullParser newParser(InputStream is) { return newParser(is, DEFAULT_CHARSET); } /** * Creates a new parser, using the given InputStream as its {@code JSON} feed. * * <p> * Please call one of the {@code setSource(...)}'s before calling other methods. * </p> * * @param is * An InputStream serves as {@code JSON} feed. Cannot be null. * @param charsetName * The character set should be assumed in which in the stream are encoded. {@link #DEFAULT_CHARSET_NAME} is assumed if null is passed. * @return {@link JsonPullParser} * @throws UnsupportedEncodingException * An unknown character set is specified. * @throws IllegalArgumentException * {@code null} has been passed in where not applicable. */ public static JsonPullParser newParser(InputStream is, String charsetName) throws UnsupportedEncodingException { if (is == null) { throw new IllegalArgumentException("'is' must not be null."); } try { final Charset charset = (charsetName == null) ? null : Charset.forName(charsetName); return newParser(is, charset); } catch (UnsupportedCharsetException e) { throw new UnsupportedEncodingException(e.getCharsetName()); } } /** * Creates a new parser, using the given InputStream as its {@code JSON} feed. * * <p> * Please call one of the {@code setSource(...)}'s before calling other methods. * </p> * * @param is * An InputStream serves as {@code JSON} feed. Cannot be null. * @param charset * The character set should be assumed in which in the stream are encoded. {@link #DEFAULT_CHARSET_NAME} is assumed if null is passed. * @return {@link JsonPullParser} * @throws IllegalArgumentException * {@code null} has been passed in where not applicable. */ public static JsonPullParser newParser(InputStream is, Charset charset) { if (is == null) { throw new IllegalArgumentException("'is' must not be null."); } final Reader reader = new InputStreamReader(is, (charset == null) ? DEFAULT_CHARSET : charset); return newParser(reader); } /** * Creates a new parser, using the given InputStream as its {@code JSON} feed. * * <p> * Please call one of the {@code setSource(...)}'s before calling other methods. * </p> * * @param json * An InputStream serves as {@code JSON} feed. Cannot be null. * @return {@link JsonPullParser} * @throws IllegalArgumentException * {@code null} has been passed in where not applicable. */ public static JsonPullParser newParser(String json) { if (json == null) { throw new IllegalArgumentException("'json' must not be null."); } return newParser(new StringReader(json)); } /** * Creates a new parser, using the given InputStream as its {@code JSON} feed. * * <p> * Please call one of the {@code setSource(...)}'s before calling other methods. * </p> * * @param reader * A Reader. Cannot be null. * @return {@link JsonPullParser} * @throws IllegalArgumentException * {@code null} has been passed in where not applicable. */ public static JsonPullParser newParser(Reader reader) { if (reader == null) { throw new IllegalArgumentException("'reader' must not be null."); } BufferedReader br = (reader instanceof BufferedReader) ? (BufferedReader) reader : new BufferedReader( reader); JsonPullParser parser = new JsonPullParser(); parser.setSource(br); return parser; } JsonPullParser() { stack.push(State.ORIGIN); } /** * Sets an Reader as the {@code JSON} feed. * @param reader * A Reader. Cannot be null. */ void setSource(Reader reader) { if (reader == null) { throw new IllegalArgumentException("'reader' must not be null."); } br = (reader instanceof BufferedReader) ? (BufferedReader) reader : new BufferedReader( reader); } /** * Sets if original-equivalent data should be saved as parsing goes. * @return this ({@link JsonPullParser}) * @author vvakame */ public JsonPullParser setLogEnable() { logEnabled = true; slices = new ArrayList<JsonSlice>(); return this; } /** * Advances by one element. * * <p> * This method is not a true lookahead operation, and has adverse effects on the return value of getValue* family. You have been warned. * </p> * <p> * Its return value does not mutate until you call {@link #getEventType()}. * </p> * * @return The next token type. * @throws IOException * {@code JSON} data cannot read successfully. * @throws JsonFormatException * The data is malformed */ public State lookAhead() throws IOException, JsonFormatException { if (lookAhead == null) { lookAhead = getEventType(); } return lookAhead; } /** * Returns the current token type. * * @return The token type in the hand. * @throws IOException * {@code JSON} data cannot read successfully. * @throws JsonFormatException * The data is malformed */ public State getEventType() throws IOException, JsonFormatException { if (lookAhead != null) { State tmp = lookAhead; lookAhead = null; return tmp; } boolean saveSlice = true; char c = getNextChar(); switch (stack.pop()) { case ORIGIN: switch (c) { case '{': stack.push(State.START_HASH); break; case '[': stack.push(State.START_ARRAY); break; default: throw new JsonFormatException("unexpected token. token=" + c, this); } break; case START_ARRAY: stack.push(State.START_ARRAY); switch (c) { case '{': stack.push(State.START_HASH); break; case '[': stack.push(State.START_ARRAY); break; case '"': stack.push(State.VALUE_STRING); valueStr = getNextString(); break; case ']': stack.push(State.END_ARRAY); break; case 't': expectNextChar('r'); expectNextChar('u'); expectNextChar('e'); stack.push(State.VALUE_BOOLEAN); valueBoolean = true; break; case 'f': expectNextChar('a'); expectNextChar('l'); expectNextChar('s'); expectNextChar('e'); stack.push(State.VALUE_BOOLEAN); valueBoolean = false; break; case 'n': expectNextChar('u'); expectNextChar('l'); expectNextChar('l'); stack.push(State.VALUE_NULL); break; default: // ?? try { fetchNextNumeric(); break; } catch (NumberFormatException e) { throw new JsonFormatException(e, this); } } break; case START_HASH: stack.push(State.START_HASH); switch (c) { case '{': stack.push(State.START_HASH); break; case '[': stack.push(State.START_ARRAY); break; case '}': stack.push(State.END_HASH); break; case '"': stack.push(State.KEY); valueStr = getNextString(); c = getNextChar(); if (c != ':') { throw new JsonFormatException("unexpected token. token=" + c, this); } break; default: throw new JsonFormatException("unexpected token. token=" + c, this); } break; case END_ARRAY: if (!State.START_ARRAY.equals(stack.pop())) { throw new JsonFormatException("unexpected token.", this); } switch (c) { case ',': getEventType(); saveSlice = false; break; case ']': stack.push(State.END_ARRAY); break; case '}': stack.push(State.END_HASH); break; default: throw new JsonFormatException("unexpected token. token=" + c, this); } break; case END_HASH: if (!State.START_HASH.equals(stack.pop())) { throw new JsonFormatException("unexpected token.", this); } switch (c) { case ',': getEventType(); saveSlice = false; break; case ']': stack.push(State.END_ARRAY); break; case '}': stack.push(State.END_HASH); break; default: throw new JsonFormatException("unexpected token. token=" + c, this); } break; case KEY: switch (c) { case '"': stack.push(State.VALUE_STRING); valueStr = getNextString(); break; case '[': stack.push(State.START_ARRAY); break; case '{': stack.push(State.START_HASH); break; case 't': expectNextChar('r'); expectNextChar('u'); expectNextChar('e'); stack.push(State.VALUE_BOOLEAN); valueBoolean = true; break; case 'f': expectNextChar('a'); expectNextChar('l'); expectNextChar('s'); expectNextChar('e'); stack.push(State.VALUE_BOOLEAN); valueBoolean = false; break; case 'n': expectNextChar('u'); expectNextChar('l'); expectNextChar('l'); stack.push(State.VALUE_NULL); break; default: // ?? try { fetchNextNumeric(); break; } catch (NumberFormatException e) { throw new JsonFormatException(e, this); } } break; case VALUE_STRING: case VALUE_LONG: case VALUE_DOUBLE: case VALUE_NULL: case VALUE_BOOLEAN: switch (c) { case ',': getEventType(); saveSlice = false; break; case '}': stack.push(State.END_HASH); break; case ']': stack.push(State.END_ARRAY); break; default: throw new JsonFormatException("unexpected token. token=" + c, this); } break; default: throw new JsonFormatException("unexpected token.", this); } current = stack.peek(); if (logEnabled && saveSlice) { saveSlices(); } return current; } void saveSlices() throws JsonFormatException { switch (current) { case START_ARRAY: case END_ARRAY: case START_HASH: case END_HASH: case VALUE_NULL: slices.add(new JsonSlice(current)); break; case KEY: case VALUE_STRING: slices.add(new JsonSlice(current, valueStr)); break; case VALUE_BOOLEAN: slices.add(new JsonSlice(current, valueBoolean)); break; case VALUE_DOUBLE: slices.add(new JsonSlice(current, valueDouble)); break; case VALUE_LONG: slices.add(new JsonSlice(current, valueLong)); break; default: throw new JsonFormatException("unknown State=" + current, this); } } /** * Returns the size of the {@link JsonSlice} in the hand.<br> * Consider and compensates the effect of {@link #lookAhead()} (i.e. it consumes the slice by 1.) * @return The current slice size. * @author vvakame */ public int getSliceSize() { if (slices == null) { return -1; } else { return lookAhead == null ? slices.size() : slices.size() - 1; } } /** * Reads and discards the next value.<br> * We: * a) discard the whole element if we're standing on an array ({@link State#START_HASH}) or a hash ({@link State#START_HASH},) or * b) discard the key and corresponding value if we're standing on a key ({@link State#KEY},) or * c) discard the value itself if we're standing on a value, or * d) throw {@link IllegalStateException} as we're in an unexpected situation. * * @throws IOException * {@code JSON} data cannot read successfully. * @throws JsonFormatException * The data is malformed * @throws IllegalStateException when it stumbles upon an unexpected {@link State}. */ public void discardValue() throws IOException, JsonFormatException, IllegalStateException { State state = lookAhead(); switch (state) { case START_ARRAY: discardArrayToken(); break; case START_HASH: discardHashToken(); break; case KEY: getEventType(); discardValue(); break; case VALUE_NULL: case VALUE_STRING: case VALUE_BOOLEAN: case VALUE_LONG: case VALUE_DOUBLE: getEventType(); break; default: throw new IllegalStateException("unexpected token. token=" + state); } } /** * Reads and discards the next array/hash or null.<br> * Throws {@link IllegalStateException} otherwise. * @throws IOException * {@code JSON} data cannot read successfully. * @throws JsonFormatException * The data is malformed * @throws IllegalStateException when it stumbles upon an unexpected {@link State}. */ public void discardArrayToken() throws IOException, JsonFormatException, IllegalStateException { State state = lookAhead(); switch (state) { case START_ARRAY: getEventType(); while ((state = lookAhead()) != State.END_ARRAY) { switch (state) { case START_ARRAY: discardArrayToken(); break; case START_HASH: discardHashToken(); break; case VALUE_NULL: case VALUE_STRING: case VALUE_BOOLEAN: case VALUE_LONG: case VALUE_DOUBLE: getEventType(); break; default: throw new IllegalStateException("unexpected token. token=" + state); } } getEventType(); break; case VALUE_NULL: getEventType(); break; default: throw new IllegalStateException("unexpected token. token=" + state); } } /** * Reads and discards the next hash or null.<br> * Throws {@link IllegalStateException} otherwise. * @throws IOException * {@code JSON} data cannot read successfully. * @throws JsonFormatException * The data is malformed * @throws IllegalStateException when it stumbles upon an unexpected {@link State}. */ public void discardHashToken() throws IOException, JsonFormatException, IllegalStateException { State state = lookAhead(); switch (state) { case START_HASH: getEventType(); while ((state = lookAhead()) != State.END_HASH) { switch (state) { case START_ARRAY: discardArrayToken(); break; case START_HASH: discardHashToken(); break; case KEY: case VALUE_NULL: case VALUE_STRING: case VALUE_BOOLEAN: case VALUE_LONG: case VALUE_DOUBLE: getEventType(); break; default: throw new IllegalStateException("unexpected token. token=" + state); } } getEventType(); break; case VALUE_NULL: getEventType(); break; default: throw new IllegalStateException("unexpected token. token=" + state); } } /** * Get the current value as string.<br> * * <p> * Please call if {@link JsonPullParser#getEventType()} returns {@link State#KEY} or * {@link State#VALUE_STRING}. * </p> * * @return The current value read as string. */ public String getValueString() { if (current == State.KEY) { return valueStr; } else if (current == State.VALUE_STRING) { return valueStr; } else if (current == State.VALUE_NULL) { return null; } else { throw new IllegalStateException("unexpected state. state=" + current); } } /** * Get the current value as integer.<br> * * <p> * Please call if {@link JsonPullParser#getEventType()} returns {@link State#VALUE_LONG}. * </p> * * @return The current value read as integer. * @throws NullPointerException The current value is null ({@link #getEventType()} returns {@link State#VALUE_NULL}.) */ public long getValueLong() throws NullPointerException { if (current == State.VALUE_LONG) { return valueLong; } else if (current == State.VALUE_NULL) { return -1; } else { throw new IllegalStateException("unexpected state. state=" + current); } } /** * Get the current value as double-precison floating point number.<br> * * <p> * Please call if {@link JsonPullParser#getEventType()} returns {@link State#VALUE_DOUBLE}. * </p> * * @return The current value read as double-precison floating point number. * @throws NullPointerException The current value is null ({@link #getEventType()} returns {@link State#VALUE_NULL}.) */ public double getValueDouble() throws NullPointerException { if (current == State.VALUE_DOUBLE) { return valueDouble; } else if (current == State.VALUE_NULL) { return -1; } else if (current == State.VALUE_LONG) { return valueLong; } else { throw new IllegalStateException("unexpected state. state=" + current); } } /** * Get the current value as boolean.<br> * * <p> * Please call if {@link JsonPullParser#getEventType()} returns {@link State#VALUE_BOOLEAN}. * </p> * * @return The current value read as boolean. * @throws NullPointerException The current value is null ({@link #getEventType()} returns {@link State#VALUE_NULL}.) */ public boolean getValueBoolean() throws NullPointerException { if (current == State.VALUE_BOOLEAN) { return valueBoolean; } else if (current == State.VALUE_NULL) { return false; } else { throw new IllegalStateException("unexpected state. state=" + current); } } private char getNextChar() throws IOException { br.mark(1); char c = (char) br.read(); while (c == ' ' || c == '\r' || c == '\n' || c == '\t') { br.mark(1); c = (char) br.read(); } return c; } private void expectNextChar(char expect) throws IOException, JsonFormatException { char c = getNextChar(); if (c != expect) { throw new JsonFormatException("unexpected char. expected=" + expect + ", char=" + c, this); } } StringBuilder stb = new StringBuilder(); private void expectSignOrDigitAfterE() throws IOException, JsonFormatException { char c = (char) br.read(); switch (c) { case '+': case '-': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': br.mark(1); stb.append(c); break; default: throw new JsonFormatException("unexpected char. expected '+' or '-' or digit", this); } } private void fetchNextNumeric() throws IOException, JsonFormatException { stb.setLength(0); br.reset(); char c; boolean d = false; loop: while (true) { c = (char) br.read(); switch (c) { case '.': case 'e': case 'E': d = true; case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': case '-': break; default: br.reset(); break loop; } br.mark(1); stb.append(c); if (c == 'e' || c == 'E') { expectSignOrDigitAfterE(); } } if (d) { valueDouble = Double.parseDouble(stb.toString()); stack.push(State.VALUE_DOUBLE); } else { valueLong = Long.parseLong(stb.toString()); stack.push(State.VALUE_LONG); } } private String getNextString() throws IOException { stb.setLength(0); char c; loop: while (true) { c = (char) br.read(); switch (c) { case '\\': br.mark(5); c = (char) br.read(); switch (c) { case '/': case '"': case '\\': break; case 'n': c = '\n'; break; case 'r': c = '\r'; break; case 't': c = '\t'; break; case 'b': c = '\b'; break; case 'f': c = '\f'; break; case 'u': c = 0; int r; for (int i = 0; i < 4; i++) { r = getNextStringHelper(br.read()); if (r == -1) { c = '\\'; br.reset(); break; } c <<= 4; c += r; } break; default: c = '\\'; br.reset(); break; } break; case '"': break loop; default: break; } stb.append(c); } return stb.toString(); } private int getNextStringHelper(int c) { if ('0' <= c && c <= '9') { return c - '0'; } else if ('a' <= c && c <= 'f') { return c - 'a' + 10; } else if ('A' <= c && c <= 'F') { return c - 'A' + 10; } else { return -1; } } /** * @return the logEnable * @category accessor */ public boolean isLogEnabled() { return logEnabled; } /** * @return the slices * @category accessor */ public List<JsonSlice> getSlices() { return slices; } }