TransliteratorIDParser.java
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**********************************************************************
* Copyright (c) 2002-2011, International Business Machines Corporation
* and others. All Rights Reserved.
**********************************************************************
* Date Name Description
* 01/14/2002 aliu Creation.
**********************************************************************
*/
package com.ibm.icu.text;
import com.ibm.icu.impl.PatternProps;
import com.ibm.icu.impl.Utility;
import com.ibm.icu.util.CaseInsensitiveString;
import java.text.ParsePosition;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Parsing component for transliterator IDs. This class contains only static members; it cannot be
* instantiated. Methods in this class parse various ID formats, including the following:
*
* <p>A basic ID, which contains source, target, and variant, but no filter and no explicit inverse.
* Examples include "Latin-Greek/UNGEGN" and "Null".
*
* <p>A single ID, which is a basic ID plus optional filter and optional explicit inverse. Examples
* include "[a-zA-Z] Latin-Greek" and "Lower (Upper)".
*
* <p>A compound ID, which is a sequence of one or more single IDs, separated by semicolons, with
* optional forward and reverse global filters. The global filters are UnicodeSet patterns prepended
* or appended to the IDs, separated by semicolons. An appended filter must be enclosed in
* parentheses and applies in the reverse direction.
*
* @author Alan Liu
*/
class TransliteratorIDParser {
private static final char ID_DELIM = ';';
private static final char TARGET_SEP = '-';
private static final char VARIANT_SEP = '/';
private static final char OPEN_REV = '(';
private static final char CLOSE_REV = ')';
private static final String ANY = "Any";
private static final int FORWARD = Transliterator.FORWARD;
private static final int REVERSE = Transliterator.REVERSE;
private static final Map<CaseInsensitiveString, String> SPECIAL_INVERSES =
Collections.synchronizedMap(new HashMap<CaseInsensitiveString, String>());
/**
* A structure containing the parsed data of a filtered ID, that is, a basic ID optionally with
* a filter.
*
* <p>'source' and 'target' will always be non-null. The 'variant' will be non-null only if a
* non-empty variant was parsed.
*
* <p>'sawSource' is true if there was an explicit source in the parsed id. If there was no
* explicit source, then an implied source of ANY is returned and 'sawSource' is set to false.
*
* <p>'filter' is the parsed filter pattern, or null if there was no filter.
*/
private static class Specs {
public String source; // not null
public String target; // not null
public String variant; // may be null
public String filter; // may be null
public boolean sawSource;
Specs(String s, String t, String v, boolean sawS, String f) {
source = s;
target = t;
variant = v;
sawSource = sawS;
filter = f;
}
}
/**
* A structure containing the canonicalized data of a filtered ID, that is, a basic ID
* optionally with a filter.
*
* <p>'canonID' is always non-null. It may be the empty string "". It is the id that should be
* assigned to the created transliterator. It _cannot_ be instantiated directly.
*
* <p>'basicID' is always non-null and non-empty. It is always of the form S-T or S-T/V. It is
* designed to be fed to low-level instantiation code that only understands these two formats.
*
* <p>'filter' may be null, if there is none, or non-null and non-empty.
*/
static class SingleID {
public String canonID;
public String basicID;
public String filter;
SingleID(String c, String b, String f) {
canonID = c;
basicID = b;
filter = f;
}
SingleID(String c, String b) {
this(c, b, null);
}
Transliterator getInstance() {
Transliterator t;
if (basicID == null || basicID.length() == 0) {
t = Transliterator.getBasicInstance("Any-Null", canonID);
} else {
t = Transliterator.getBasicInstance(basicID, canonID);
}
if (t != null) {
if (filter != null) {
t.setFilter(new UnicodeSet(filter));
}
}
return t;
}
}
/**
* Parse a filter ID, that is, an ID of the general form "[f1] s1-t1/v1", with the filters
* optional, and the variants optional.
*
* @param id the id to be parsed
* @param pos INPUT-OUTPUT parameter. On input, the position of the first character to parse. On
* output, the position after the last character parsed.
* @return a SingleID object or null if the parse fails
*/
public static SingleID parseFilterID(String id, int[] pos) {
int start = pos[0];
Specs specs = parseFilterID(id, pos, true);
if (specs == null) {
pos[0] = start;
return null;
}
// Assemble return results
SingleID single = specsToID(specs, FORWARD);
single.filter = specs.filter;
return single;
}
/**
* Parse a single ID, that is, an ID of the general form "[f1] s1-t1/v1 ([f2] s2-t3/v2)", with
* the parenthesized element optional, the filters optional, and the variants optional.
*
* @param id the id to be parsed
* @param pos INPUT-OUTPUT parameter. On input, the position of the first character to parse. On
* output, the position after the last character parsed.
* @param dir the direction. If the direction is REVERSE then the SingleID is constructed for
* the reverse direction.
* @return a SingleID object or null
*/
public static SingleID parseSingleID(String id, int[] pos, int dir) {
int start = pos[0];
// The ID will be of the form A, A(), A(B), or (B), where
// A and B are filter IDs.
Specs specsA = null;
Specs specsB = null;
boolean sawParen = false;
// On the first pass, look for (B) or (). If this fails, then
// on the second pass, look for A, A(B), or A().
for (int pass = 1; pass <= 2; ++pass) {
if (pass == 2) {
specsA = parseFilterID(id, pos, true);
if (specsA == null) {
pos[0] = start;
return null;
}
}
if (Utility.parseChar(id, pos, OPEN_REV)) {
sawParen = true;
if (!Utility.parseChar(id, pos, CLOSE_REV)) {
specsB = parseFilterID(id, pos, true);
// Must close with a ')'
if (specsB == null || !Utility.parseChar(id, pos, CLOSE_REV)) {
pos[0] = start;
return null;
}
}
break;
}
}
// Assemble return results
SingleID single;
if (sawParen) {
if (dir == FORWARD) {
single = specsToID(specsA, FORWARD);
single.canonID =
single.canonID + OPEN_REV + specsToID(specsB, FORWARD).canonID + CLOSE_REV;
if (specsA != null) {
single.filter = specsA.filter;
}
} else {
single = specsToID(specsB, FORWARD);
single.canonID =
single.canonID + OPEN_REV + specsToID(specsA, FORWARD).canonID + CLOSE_REV;
if (specsB != null) {
single.filter = specsB.filter;
}
}
} else {
// assert(specsA != null);
if (dir == FORWARD) {
single = specsToID(specsA, FORWARD);
} else {
single = specsToSpecialInverse(specsA);
if (single == null) {
single = specsToID(specsA, REVERSE);
}
}
single.filter = specsA.filter;
}
return single;
}
/**
* Parse a global filter of the form "[f]" or "([f])", depending on 'withParens'.
*
* @param id the pattern the parse
* @param pos INPUT-OUTPUT parameter. On input, the position of the first character to parse. On
* output, the position after the last character parsed.
* @param dir the direction.
* @param withParens INPUT-OUTPUT parameter. On entry, if withParens[0] is 0, then parens are
* disallowed. If it is 1, then parens are requires. If it is -1, then parens are optional,
* and the return result will be set to 0 or 1.
* @param canonID OUTPUT parameter. The pattern for the filter added to the canonID, either at
* the end, if dir is FORWARD, or at the start, if dir is REVERSE. The pattern will be
* enclosed in parentheses if appropriate, and will be suffixed with an ID_DELIM character.
* May be null.
* @return a UnicodeSet object or null. A non-null results indicates a successful parse,
* regardless of whether the filter applies to the given direction. The caller should
* discard it if withParens != (dir == REVERSE).
*/
public static UnicodeSet parseGlobalFilter(
String id, int[] pos, int dir, int[] withParens, StringBuilder canonID) {
UnicodeSet filter = null;
int start = pos[0];
if (withParens[0] == -1) {
withParens[0] = Utility.parseChar(id, pos, OPEN_REV) ? 1 : 0;
} else if (withParens[0] == 1) {
if (!Utility.parseChar(id, pos, OPEN_REV)) {
pos[0] = start;
return null;
}
}
pos[0] = PatternProps.skipWhiteSpace(id, pos[0]);
if (UnicodeSet.resemblesPattern(id, pos[0])) {
ParsePosition ppos = new ParsePosition(pos[0]);
try {
filter = new UnicodeSet(id, ppos, null);
} catch (IllegalArgumentException e) {
pos[0] = start;
return null;
}
String pattern = id.substring(pos[0], ppos.getIndex());
pos[0] = ppos.getIndex();
if (withParens[0] == 1 && !Utility.parseChar(id, pos, CLOSE_REV)) {
pos[0] = start;
return null;
}
// In the forward direction, append the pattern to the
// canonID. In the reverse, insert it at zero, and invert
// the presence of parens ("A" <-> "(A)").
if (canonID != null) {
if (dir == FORWARD) {
if (withParens[0] == 1) {
pattern = String.valueOf(OPEN_REV) + pattern + CLOSE_REV;
}
canonID.append(pattern + ID_DELIM);
} else {
if (withParens[0] == 0) {
pattern = String.valueOf(OPEN_REV) + pattern + CLOSE_REV;
}
canonID.insert(0, pattern + ID_DELIM);
}
}
}
return filter;
}
/**
* Parse a compound ID, consisting of an optional forward global filter, a separator, one or
* more single IDs delimited by separators, an an optional reverse global filter. The separator
* is a semicolon. The global filters are UnicodeSet patterns. The reverse global filter must be
* enclosed in parentheses.
*
* @param id the pattern the parse
* @param dir the direction.
* @param canonID OUTPUT parameter that receives the canonical ID, consisting of canonical IDs
* for all elements, as returned by parseSingleID(), separated by semicolons. Previous
* contents are discarded.
* @param list OUTPUT parameter that receives a list of SingleID objects representing the parsed
* IDs. Previous contents are discarded.
* @param globalFilter OUTPUT parameter that receives a pointer to a newly created global filter
* for this ID in this direction, or null if there is none.
* @return true if the parse succeeds, that is, if the entire id is consumed without syntax
* error.
*/
public static boolean parseCompoundID(
String id,
int dir,
StringBuilder canonID,
List<SingleID> list,
UnicodeSet[] globalFilter) {
int[] pos = new int[] {0};
int[] withParens = new int[1];
list.clear();
UnicodeSet filter;
globalFilter[0] = null;
canonID.setLength(0);
// Parse leading global filter, if any
withParens[0] = 0; // parens disallowed
filter = parseGlobalFilter(id, pos, dir, withParens, canonID);
if (filter != null) {
if (!Utility.parseChar(id, pos, ID_DELIM)) {
// Not a global filter; backup and resume
canonID.setLength(0);
pos[0] = 0;
}
if (dir == FORWARD) {
globalFilter[0] = filter;
}
}
boolean sawDelimiter = true;
for (; ; ) {
SingleID single = parseSingleID(id, pos, dir);
if (single == null) {
break;
}
if (dir == FORWARD) {
list.add(single);
} else {
list.add(0, single);
}
if (!Utility.parseChar(id, pos, ID_DELIM)) {
sawDelimiter = false;
break;
}
}
if (list.size() == 0) {
return false;
}
// Construct canonical ID
for (int i = 0; i < list.size(); ++i) {
SingleID single = list.get(i);
canonID.append(single.canonID);
if (i != (list.size() - 1)) {
canonID.append(ID_DELIM);
}
}
// Parse trailing global filter, if any, and only if we saw
// a trailing delimiter after the IDs.
if (sawDelimiter) {
withParens[0] = 1; // parens required
filter = parseGlobalFilter(id, pos, dir, withParens, canonID);
if (filter != null) {
// Don't require trailing ';', but parse it if present
Utility.parseChar(id, pos, ID_DELIM);
if (dir == REVERSE) {
globalFilter[0] = filter;
}
}
}
// Trailing unparsed text is a syntax error
pos[0] = PatternProps.skipWhiteSpace(id, pos[0]);
if (pos[0] != id.length()) {
return false;
}
return true;
}
/**
* Returns the list of Transliterator objects for the given list of SingleID objects.
*
* @param ids list vector of SingleID objects.
* @return Actual transliterators for the list of SingleIDs
*/
static List<Transliterator> instantiateList(List<SingleID> ids) {
Transliterator t;
List<Transliterator> translits = new ArrayList<Transliterator>();
for (SingleID single : ids) {
if (single.basicID.length() == 0) {
continue;
}
t = single.getInstance();
if (t == null) {
throw new IllegalArgumentException("Illegal ID " + single.canonID);
}
translits.add(t);
}
// An empty list is equivalent to a Null transliterator.
if (translits.size() == 0) {
t = Transliterator.getBasicInstance("Any-Null", null);
if (t == null) {
// Should never happen
throw new IllegalArgumentException("Internal error; cannot instantiate Any-Null");
}
translits.add(t);
}
return translits;
}
/**
* Parse an ID into pieces. Take IDs of the form T, T/V, S-T, S-T/V, or S/V-T. If the source is
* missing, return a source of ANY.
*
* @param id the id string, in any of several forms
* @return an array of 4 strings: source, target, variant, and isSourcePresent. If the source is
* not present, ANY will be given as the source, and isSourcePresent will be null. Otherwise
* isSourcePresent will be non-null. The target may be empty if the id is not well-formed.
* The variant may be empty.
*/
public static String[] IDtoSTV(String id) {
String source = ANY;
String target = null;
String variant = "";
int sep = id.indexOf(TARGET_SEP);
int var = id.indexOf(VARIANT_SEP);
if (var < 0) {
var = id.length();
}
boolean isSourcePresent = false;
if (sep < 0) {
// Form: T/V or T (or /V)
target = id.substring(0, var);
variant = id.substring(var);
} else if (sep < var) {
// Form: S-T/V or S-T (or -T/V or -T)
if (sep > 0) {
source = id.substring(0, sep);
isSourcePresent = true;
}
target = id.substring(++sep, var);
variant = id.substring(var);
} else {
// Form: (S/V-T or /V-T)
if (var > 0) {
source = id.substring(0, var);
isSourcePresent = true;
}
variant = id.substring(var, sep++);
target = id.substring(sep);
}
if (variant.length() > 0) {
variant = variant.substring(1);
}
return new String[] {source, target, variant, isSourcePresent ? "" : null};
}
/**
* Given source, target, and variant strings, concatenate them into a full ID. If the source is
* empty, then "Any" will be used for the source, so the ID will always be of the form s-t/v or
* s-t.
*/
public static String STVtoID(String source, String target, String variant) {
StringBuilder id = new StringBuilder(source);
if (id.length() == 0) {
id.append(ANY);
}
id.append(TARGET_SEP).append(target);
if (variant != null && variant.length() != 0) {
id.append(VARIANT_SEP).append(variant);
}
return id.toString();
}
/**
* Register two targets as being inverses of one another. For example, calling
* registerSpecialInverse("NFC", "NFD", true) causes Transliterator to form the following
* inverse relationships:
*
* <pre>NFC => NFD
* Any-NFC => Any-NFD
* NFD => NFC
* Any-NFD => Any-NFC</pre>
*
* (Without the special inverse registration, the inverse of NFC would be NFC-Any.) Note that
* NFD is shorthand for Any-NFD, but that the presence or absence of "Any-" is preserved.
*
* <p>The relationship is symmetrical; registering (a, b) is equivalent to registering (b, a).
*
* <p>The relevant IDs must still be registered separately as factories or classes.
*
* <p>Only the targets are specified. Special inverses always have the form Any-Target1 <=>
* Any-Target2. The target should have canonical casing (the casing desired to be produced when
* an inverse is formed) and should contain no whitespace or other extraneous characters.
*
* @param target the target against which to register the inverse
* @param inverseTarget the inverse of target, that is Any-target.getInverse() =>
* Any-inverseTarget
* @param bidirectional if true, register the reverse relation as well, that is,
* Any-inverseTarget.getInverse() => Any-target
*/
public static void registerSpecialInverse(
String target, String inverseTarget, boolean bidirectional) {
SPECIAL_INVERSES.put(new CaseInsensitiveString(target), inverseTarget);
if (bidirectional && !target.equalsIgnoreCase(inverseTarget)) {
SPECIAL_INVERSES.put(new CaseInsensitiveString(inverseTarget), target);
}
}
// ----------------------------------------------------------------
// Private implementation
// ----------------------------------------------------------------
/**
* Parse an ID into component pieces. Take IDs of the form T, T/V, S-T, S-T/V, or S/V-T. If the
* source is missing, return a source of ANY.
*
* @param id the id string, in any of several forms
* @param pos INPUT-OUTPUT parameter. On input, pos[0] is the offset of the first character to
* parse in id. On output, pos[0] is the offset after the last parsed character. If the
* parse failed, pos[0] will be unchanged.
* @param allowFilter if true, a UnicodeSet pattern is allowed at any location between specs or
* delimiters, and is returned as the fifth string in the array.
* @return a Specs object, or null if the parse failed. If neither source nor target was seen in
* the parsed id, then the parse fails. If allowFilter is true, then the parsed filter
* pattern is returned in the Specs object, otherwise the returned filter reference is null.
* If the parse fails for any reason null is returned.
*/
private static Specs parseFilterID(String id, int[] pos, boolean allowFilter) {
String first = null;
String source = null;
String target = null;
String variant = null;
String filter = null;
char delimiter = 0;
int specCount = 0;
int start = pos[0];
// This loop parses one of the following things with each
// pass: a filter, a delimiter character (either '-' or '/'),
// or a spec (source, target, or variant).
for (; ; ) {
pos[0] = PatternProps.skipWhiteSpace(id, pos[0]);
if (pos[0] == id.length()) {
break;
}
// Parse filters
if (allowFilter && filter == null && UnicodeSet.resemblesPattern(id, pos[0])) {
ParsePosition ppos = new ParsePosition(pos[0]);
// Parse the set to get the position.
new UnicodeSet(id, ppos, null);
filter = id.substring(pos[0], ppos.getIndex());
pos[0] = ppos.getIndex();
continue;
}
if (delimiter == 0) {
char c = id.charAt(pos[0]);
if ((c == TARGET_SEP && target == null) || (c == VARIANT_SEP && variant == null)) {
delimiter = c;
++pos[0];
continue;
}
}
// We are about to try to parse a spec with no delimiter
// when we can no longer do so (we can only do so at the
// start); break.
if (delimiter == 0 && specCount > 0) {
break;
}
String spec = Utility.parseUnicodeIdentifier(id, pos);
if (spec == null) {
// Note that if there was a trailing delimiter, we
// consume it. So Foo-, Foo/, Foo-Bar/, and Foo/Bar-
// are legal.
break;
}
switch (delimiter) {
case 0:
first = spec;
break;
case TARGET_SEP:
target = spec;
break;
case VARIANT_SEP:
variant = spec;
break;
}
++specCount;
delimiter = 0;
}
// A spec with no prior character is either source or target,
// depending on whether an explicit "-target" was seen.
if (first != null) {
if (target == null) {
target = first;
} else {
source = first;
}
}
// Must have either source or target
if (source == null && target == null) {
pos[0] = start;
return null;
}
// Empty source or target defaults to ANY
boolean sawSource = true;
if (source == null) {
source = ANY;
sawSource = false;
}
if (target == null) {
target = ANY;
}
return new Specs(source, target, variant, sawSource, filter);
}
/**
* Givens a Spec object, convert it to a SingleID object. The Spec object is a more unprocessed
* parse result. The SingleID object contains information about canonical and basic IDs.
*
* @return a SingleID; never returns null. Returned object always has 'filter' field of null.
*/
private static SingleID specsToID(Specs specs, int dir) {
String canonID = "";
String basicID = "";
String basicPrefix = "";
if (specs != null) {
StringBuilder buf = new StringBuilder();
if (dir == FORWARD) {
if (specs.sawSource) {
buf.append(specs.source).append(TARGET_SEP);
} else {
basicPrefix = specs.source + TARGET_SEP;
}
buf.append(specs.target);
} else {
buf.append(specs.target).append(TARGET_SEP).append(specs.source);
}
if (specs.variant != null) {
buf.append(VARIANT_SEP).append(specs.variant);
}
basicID = basicPrefix + buf.toString();
if (specs.filter != null) {
buf.insert(0, specs.filter);
}
canonID = buf.toString();
}
return new SingleID(canonID, basicID);
}
/**
* Given a Specs object, return a SingleID representing the special inverse of that ID. If there
* is no special inverse then return null.
*
* @return a SingleID or null. Returned object always has 'filter' field of null.
*/
private static SingleID specsToSpecialInverse(Specs specs) {
if (!specs.source.equalsIgnoreCase(ANY)) {
return null;
}
String inverseTarget = SPECIAL_INVERSES.get(new CaseInsensitiveString(specs.target));
if (inverseTarget != null) {
// If the original ID contained "Any-" then make the
// special inverse "Any-Foo"; otherwise make it "Foo".
// So "Any-NFC" => "Any-NFD" but "NFC" => "NFD".
StringBuilder buf = new StringBuilder();
if (specs.filter != null) {
buf.append(specs.filter);
}
if (specs.sawSource) {
buf.append(ANY).append(TARGET_SEP);
}
buf.append(inverseTarget);
String basicID = ANY + TARGET_SEP + inverseTarget;
if (specs.variant != null) {
buf.append(VARIANT_SEP).append(specs.variant);
basicID = basicID + VARIANT_SEP + specs.variant;
}
return new SingleID(buf.toString(), basicID);
}
return null;
}
}
// eof