367 lines
12 KiB
Java
367 lines
12 KiB
Java
/* GENERATED SOURCE. DO NOT MODIFY. */
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// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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**********************************************************************
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* Copyright (c) 2003-2011, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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* Author: Alan Liu
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* Created: September 23 2003
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* Since: ICU 2.8
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**********************************************************************
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*/
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package android.icu.impl;
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import java.text.ParsePosition;
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import android.icu.text.SymbolTable;
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import android.icu.text.UTF16;
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/**
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* An iterator that returns 32-bit code points. This class is deliberately
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* <em>not</em> related to any of the JDK or ICU4J character iterator classes
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* in order to minimize complexity.
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* @author Alan Liu
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* @hide Only a subset of ICU is exposed in Android
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*/
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public class RuleCharacterIterator {
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// TODO: Ideas for later. (Do not implement if not needed, lest the
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// code coverage numbers go down due to unused methods.)
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// 1. Add a copy constructor, equals() method, clone() method.
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// 2. Rather than return DONE, throw an exception if the end
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// is reached -- this is an alternate usage model, probably not useful.
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// 3. Return isEscaped from next(). If this happens,
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// don't keep an isEscaped member variable.
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/**
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* Text being iterated.
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*/
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private String text;
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/**
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* Position of iterator.
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*/
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private ParsePosition pos;
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/**
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* Symbol table used to parse and dereference variables. May be null.
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*/
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private SymbolTable sym;
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/**
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* Current variable expansion, or null if none.
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*/
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private String buf;
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/**
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* Position within buf[]. Meaningless if buf == null.
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*/
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private int bufPos;
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/**
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* Flag indicating whether the last character was parsed from an escape.
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*/
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private boolean isEscaped;
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/**
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* Value returned when there are no more characters to iterate.
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*/
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public static final int DONE = -1;
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/**
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* Bitmask option to enable parsing of variable names. If (options &
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* PARSE_VARIABLES) != 0, then an embedded variable will be expanded to
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* its value. Variables are parsed using the SymbolTable API.
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*/
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public static final int PARSE_VARIABLES = 1;
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/**
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* Bitmask option to enable parsing of escape sequences. If (options &
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* PARSE_ESCAPES) != 0, then an embedded escape sequence will be expanded
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* to its value. Escapes are parsed using Utility.unescapeAndLengthAt().
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*/
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public static final int PARSE_ESCAPES = 2;
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/**
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* Bitmask option to enable skipping of whitespace. If (options &
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* SKIP_WHITESPACE) != 0, then Unicode Pattern_White_Space characters will be silently
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* skipped, as if they were not present in the input.
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*/
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public static final int SKIP_WHITESPACE = 4;
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/** For use with {@link #getPos(Position)} & {@link #setPos(Position)}.
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* @hide Only a subset of ICU is exposed in Android*/
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public static final class Position {
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private String buf;
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private int bufPos;
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private int posIndex;
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};
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/**
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* Constructs an iterator over the given text, starting at the given
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* position.
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* @param text the text to be iterated
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* @param sym the symbol table, or null if there is none. If sym is null,
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* then variables will not be dereferenced, even if the PARSE_VARIABLES
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* option is set.
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* @param pos upon input, the index of the next character to return. If a
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* variable has been dereferenced, then pos will <em>not</em> increment as
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* characters of the variable value are iterated.
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*/
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public RuleCharacterIterator(String text, SymbolTable sym,
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ParsePosition pos) {
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if (text == null || pos.getIndex() > text.length()) {
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throw new IllegalArgumentException();
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}
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this.text = text;
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this.sym = sym;
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this.pos = pos;
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buf = null;
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}
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/**
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* Returns true if this iterator has no more characters to return.
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*/
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public boolean atEnd() {
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return buf == null && pos.getIndex() == text.length();
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}
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/**
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* Returns the next character using the given options, or DONE if there
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* are no more characters, and advance the position to the next
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* character.
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* @param options one or more of the following options, bitwise-OR-ed
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* together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE.
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* @return the current 32-bit code point, or DONE
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*/
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public int next(int options) {
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int c = DONE;
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isEscaped = false;
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for (;;) {
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c = _current();
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_advance(UTF16.getCharCount(c));
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if (c == SymbolTable.SYMBOL_REF && buf == null &&
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(options & PARSE_VARIABLES) != 0 && sym != null) {
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String name = sym.parseReference(text, pos, text.length());
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// If name == null there was an isolated SYMBOL_REF;
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// return it. Caller must be prepared for this.
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if (name == null) {
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break;
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}
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bufPos = 0;
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char[] chars = sym.lookup(name);
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if (chars == null) {
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buf = null;
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throw new IllegalArgumentException(
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"Undefined variable: " + name);
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}
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// Handle empty variable value
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if (chars.length == 0) {
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buf = null;
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}
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buf = new String(chars);
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continue;
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}
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if ((options & SKIP_WHITESPACE) != 0 &&
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PatternProps.isWhiteSpace(c)) {
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continue;
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}
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if (c == '\\' && (options & PARSE_ESCAPES) != 0) {
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int cpAndLength = Utility.unescapeAndLengthAt(
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getCurrentBuffer(), getCurrentBufferPos());
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if (cpAndLength < 0) {
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throw new IllegalArgumentException("Invalid escape");
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}
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c = Utility.cpFromCodePointAndLength(cpAndLength);
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jumpahead(Utility.lengthFromCodePointAndLength(cpAndLength));
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isEscaped = true;
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}
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break;
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}
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return c;
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}
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/**
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* Returns true if the last character returned by next() was
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* escaped. This will only be the case if the option passed in to
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* next() included PARSE_ESCAPED and the next character was an
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* escape sequence.
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*/
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public boolean isEscaped() {
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return isEscaped;
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}
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/**
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* Returns true if this iterator is currently within a variable expansion.
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*/
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public boolean inVariable() {
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return buf != null;
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}
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/**
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* Returns an object which, when later passed to setPos(), will
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* restore this iterator's position. Usage idiom:
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*
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* RuleCharacterIterator iterator = ...;
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* Position pos = iterator.getPos(null); // allocate position object
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* for (;;) {
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* pos = iterator.getPos(pos); // reuse position object
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* int c = iterator.next(...);
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* ...
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* }
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* iterator.setPos(pos);
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*
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* @param p a position object previously returned by {@code getPos()},
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* or null. If not null, it will be updated and returned. If
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* null, a new position object will be allocated and returned.
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* @return a position object which may be passed to setPos(), either
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* {@code p}, or if {@code p} == null, a newly-allocated object
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*/
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public Position getPos(Position p) {
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if (p == null) {
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p = new Position();
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}
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p.buf = buf;
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p.bufPos = bufPos;
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p.posIndex = pos.getIndex();
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return p;
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}
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/**
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* Restores this iterator to the position it had when getPos()
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* returned the given object.
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* @param p a position object previously returned by getPos()
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*/
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public void setPos(Position p) {
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buf = p.buf;
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pos.setIndex(p.posIndex);
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bufPos = p.bufPos;
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}
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/**
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* Skips ahead past any ignored characters, as indicated by the given
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* options. This is useful in conjunction with the lookahead() method.
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*
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* Currently, this only has an effect for SKIP_WHITESPACE.
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* @param options one or more of the following options, bitwise-OR-ed
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* together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE.
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*/
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public void skipIgnored(int options) {
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if ((options & SKIP_WHITESPACE) != 0) {
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for (;;) {
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int a = _current();
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if (!PatternProps.isWhiteSpace(a)) break;
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_advance(UTF16.getCharCount(a));
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}
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}
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}
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/**
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* Returns a string containing the remainder of the characters to be
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* returned by this iterator, without any option processing. If the
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* iterator is currently within a variable expansion, this will only
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* extend to the end of the variable expansion.
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* This method, together with getCurrentBufferPos() (which replace the former lookahead()),
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* is provided so that iterators may interoperate with string-based APIs. The typical
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* sequence of calls is to call skipIgnored(), then call these methods, then
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* parse that substring, then call jumpahead() to
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* resynchronize the iterator.
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* @return a string containing the characters to be returned by future
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* calls to next()
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*/
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public String getCurrentBuffer() {
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if (buf != null) {
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return buf;
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} else {
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return text;
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}
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}
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public int getCurrentBufferPos() {
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if (buf != null) {
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return bufPos;
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} else {
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return pos.getIndex();
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}
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}
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/**
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* Advances the position by the given number of 16-bit code units.
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* This is useful in conjunction with getCurrentBuffer()+getCurrentBufferPos()
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* (formerly lookahead()).
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* @param count the number of 16-bit code units to jump over
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*/
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public void jumpahead(int count) {
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if (count < 0) {
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throw new IllegalArgumentException();
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}
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if (buf != null) {
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bufPos += count;
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if (bufPos > buf.length()) {
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throw new IllegalArgumentException();
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}
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if (bufPos == buf.length()) {
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buf = null;
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}
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} else {
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int i = pos.getIndex() + count;
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pos.setIndex(i);
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if (i > text.length()) {
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throw new IllegalArgumentException();
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}
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}
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}
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/**
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* Returns a string representation of this object, consisting of the
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* characters being iterated, with a '|' marking the current position.
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* Position within an expanded variable is <em>not</em> indicated.
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* @return a string representation of this object
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*/
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@Override
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public String toString() {
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int b = pos.getIndex();
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return text.substring(0, b) + '|' + text.substring(b);
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}
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/**
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* Returns the current 32-bit code point without parsing escapes, parsing
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* variables, or skipping whitespace.
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* @return the current 32-bit code point
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*/
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private int _current() {
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if (buf != null) {
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return UTF16.charAt(buf, bufPos);
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} else {
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int i = pos.getIndex();
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return (i < text.length()) ? UTF16.charAt(text, i) : DONE;
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}
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}
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/**
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* Advances the position by the given amount.
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* @param count the number of 16-bit code units to advance past
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*/
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private void _advance(int count) {
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if (buf != null) {
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bufPos += count;
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if (bufPos == buf.length()) {
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buf = null;
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}
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} else {
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pos.setIndex(pos.getIndex() + count);
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if (pos.getIndex() > text.length()) {
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pos.setIndex(text.length());
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}
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}
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}
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}
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