Pretty Writer
Selebrator
7 years ago
parent
2f34d55cfc
commit
e2d8421cda
@ -0,0 +1,228 @@
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package _8.io;
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import java.io.Closeable;
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import java.io.EOFException;
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import java.io.IOException;
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import java.io.Reader;
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import java.util.Arrays;
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import static _8.io.SonState.*;
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public class SonReader implements Closeable {
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private final Reader in;
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private SonState[] stack = new SonState[32];
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private int stackTop = 0;
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private Integer rememberedChar;
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public SonReader(Reader in) {
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this.in = in;
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this.pushState(EMPTY_DOCUMENT);
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}
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public void beginObject() throws IOException {
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this.prepareValue();
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if(this.nextNonWhitespace() == '{') {
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this.pushState(EMPTY_OBJECT);
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} else {
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throw new IllegalStateException("Expected BEGIN_OBJECT");
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}
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}
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public void endObject() throws IOException {
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if(this.nextNonWhitespace() == '}') {
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this.popState();
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} else {
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throw new IllegalStateException("Expected END_OBJECT");
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}
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}
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public void beginArray() throws IOException {
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this.prepareValue();
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if(this.nextNonWhitespace() == '[') {
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this.pushState(EMPTY_ARRAY);
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} else {
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throw new IllegalStateException("Expected BEGIN_ARRAY");
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}
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}
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public void endArray() throws IOException {
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if(this.nextNonWhitespace() == ']') {
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this.popState();
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} else {
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throw new IllegalStateException("Expected END_ARRAY");
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}
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}
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public boolean hasNext() throws IOException {
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int c = this.nextNonWhitespace();
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this.rememberChar(c);
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switch(this.peekState()) {
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case EMPTY_DOCUMENT:
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case EMPTY_OBJECT:
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case NONEMPTY_DOCUMENT:
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case NONEMPTY_OBJECT:
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return c != '}';
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case EMPTY_ARRAY:
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case NONEMPTY_ARRAY:
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return c != ']';
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case DANGLING_NAME:
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default:
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throw new IllegalStateException();
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}
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}
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public String nextName() throws IOException {
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return this.readName();
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}
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public String nextValue() throws IOException {
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return this.readValue();
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}
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private String readName() throws IOException {
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this.prepareName();
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final StringBuilder name = new StringBuilder();
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int c = this.nextNonWhitespace();
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do {
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name.append((char) c);
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} while((c = this.eofRead()) != ':');
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return name.toString();
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}
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private void prepareName() throws IOException {
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SonState state = this.peekState();
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if(state == NONEMPTY_OBJECT) { // not first in an object
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this.nextChar(true);// remove , from previous value
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} else if(state != EMPTY_OBJECT) { // not in an object
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throw new IllegalStateException("Didn't expect this to be named");
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}
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this.replaceTopState(DANGLING_NAME);
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}
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private void prepareValue() throws IOException {
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SonState state = this.peekState();
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switch(state) {
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case EMPTY_DOCUMENT:
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this.replaceTopState(NONEMPTY_DOCUMENT);
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break;
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case EMPTY_ARRAY:
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this.replaceTopState(NONEMPTY_ARRAY);
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break;
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case NONEMPTY_ARRAY:
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case NONEMPTY_OBJECT:
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this.nextChar(true); // remove , from previous element
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break;
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case DANGLING_NAME:
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this.replaceTopState(NONEMPTY_OBJECT);
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break;
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default:
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throw new IllegalStateException();
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}
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}
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private String readValue() throws IOException {
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this.prepareValue();
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final StringBuilder value = new StringBuilder();
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int c = this.nextNonWhitespace();
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do {
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value.append((char) c);
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} while((c = this.eofRead()) != ',' && c != '}' && c != ']');
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this.rememberChar(c);
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return value.toString().trim();
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}
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public void skipValue() throws IOException {
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this.prepareValue();
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int count = 0;
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int c;
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do {
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c = this.nextNonWhitespace();
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if(c == '{') {
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this.pushState(EMPTY_OBJECT);
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count++;
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} else if(c == '[') {
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this.pushState(EMPTY_ARRAY);
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count++;
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} else if(c == '}') {
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this.popState();
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count--;
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} else if(c == ']') {
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this.popState();
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count--;
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} else {
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this.nextValue();
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}
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} while(count != 0);
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}
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@Override
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public void close() throws IOException {
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this.in.close();
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this.stackTop = 1;
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this.stack[0] = CLOSED;
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}
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/* character stream management */
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private int nextNonWhitespace() throws IOException {
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int read;
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do {
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read = this.nextChar(true);
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} while(read == ' ' || read == '\t' || read == '\n');
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return read;
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}
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private int nextChar(boolean remembered) throws IOException {
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if(this.rememberedChar != null) {
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if(remembered) {
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int top = this.rememberedChar;
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this.rememberedChar = null;
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return top;
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} else {
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this.rememberedChar = null;
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}
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}
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return eofRead();
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}
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private int eofRead() throws IOException {
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int read = this.in.read();
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if(read == -1) {
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throw new EOFException();
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}
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return read;
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}
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private void rememberChar(int c) {
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if(this.rememberedChar != null) {
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throw new IllegalStateException("Already remembering a char");
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}
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this.rememberedChar = c;
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}
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/* state management */
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private SonState peekState() {
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return this.stack[this.stackTop - 1];
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}
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private SonState popState() {
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return this.stack[--this.stackTop];
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}
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private void pushState(SonState newTop) {
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if(this.stackTop >= this.stack.length) {
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this.stack = Arrays.copyOf(this.stack, this.stackTop * 2);
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}
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this.stack[this.stackTop++] = newTop;
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}
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private void replaceTopState(SonState newTop) {
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this.stack[this.stackTop - 1] = newTop;
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}
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}
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