package Breccia.Web.imager;
import java.nio.file.Path;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import static Java.Nodes.hasName;
import static Java.Nodes.isElement;
import static Java.Nodes.textChildFlat;
import static Java.Patterns.metacharacters;
import static Java.StringBuilding.clear;
import static java.util.regex.Pattern.CASE_INSENSITIVE;
import static java.util.regex.Pattern.DOTALL;
import static java.util.regex.Pattern.MULTILINE;
import static java.util.regex.Pattern.UNICODE_CASE;
/** A translator of regular-expression patterns from Breccian to compiled Javanese form.
*/
class PatternCompiler {
PatternCompiler( final ImageMould<?> mould ) { this.mould = mould; }
static final String anchoredPrefix_perfect = "^(?: )*";
static final String anchoredPrefix_titling = "^(?: )*"+"[\u2500-\u259F].*?\\R(?: )* {1,3}";
static final String anchoredPrefix_either = "^(?: )*(?:[\u2500-\u259F].*?\\R(?: )* {1,3})?";
/** Returns the Java compilation of `eP`, with {@linkplain Pattern#flags() match flags}
* derived from the `matchModifiers`.
*
* @param eP The image of a regular-expression pattern within a pattern matcher.
* @param matchModifiers The match modifiers, or an empty string if there are none.
* @throws PatternSyntaxException
* As for {@linkplain Pattern#compile(String,int) Pattern.compile}.
*/
final Pattern compile( final Node eP, final String matchModifiers, final Path sourceFile )
throws FailedInterpolation {
// Match flags
// ───────────
int flags = MULTILINE; // [MLM]
final boolean toExpandWhitespace; { // Whether expansive whitespace mode is enabled.
boolean pIsGiven = false;
final int mN = matchModifiers.length();
for( int m = 0; m < mN; ++m ) switch( matchModifiers.charAt( m )) {
case 'i' -> flags |= CASE_INSENSITIVE | UNICODE_CASE;
case 's' -> flags |= DOTALL;
case 'p' -> pIsGiven = true;
default -> {
throw new IllegalArgumentException( // Unexpected, because the Breccia parser
"Match modifiers `" + matchModifiers + '`' ); }} // should have caught it.
toExpandWhitespace = pIsGiven; }
// Pattern
// ───────
final StringBuilder bP = clear( stringBuilder ); // The Java translation of `eP`.
for( Node n = eP.getFirstChild(); n != null; n = n.getNextSibling() ) {
assert isElement( n ); // ↘ for reason
switch( n.getLocalName()/* ≠ null, given the assertion above */) { // [NSC]
case "AnchoredPrefix" -> {
final String tF = textChildFlat( n );
assert tF.length() == 2 && tF.charAt(0) == '^';
bP.append( switch( tF.charAt( 1 )) {
case '*' -> anchoredPrefix_perfect;
case '+' -> anchoredPrefix_titling;
case '^' -> anchoredPrefix_either;
default -> throw new IllegalStateException(); }); }
case "Granum" -> {
final String tF = textChildFlat( n );
assert hasNoMetacharacter( tF, 0 );
append( tF, bP, toExpandWhitespace ); }
case "BackslashedSpecial" -> {
final String tF = textChildFlat( n );
final Matcher m = numberedCharacterBackslashMatcher.reset( tF );
if( m.matches() ) {
bP.append( "\\x{" );
bP.append( m.group( 1 ));
bP.append( '}' ); }
else bP.append( tF ); }
case "Literalizer" -> {
bP.append( '\\' ); // The backslash part,
n = n.getNextSibling(); // and skipping past it.
assert hasName( "Granum", n ); /* Always that backslash is followed
directly by a `Granum` that starts with the literalized character. */
final String tF = textChildFlat( n );
bP.append( tF.charAt( 0 )); // The literalized character, plus
if( tF.length() > 1 ) { // any remainder of the `Granum`.
assert hasNoMetacharacter( tF, 1 );
append( tF, 1, bP, toExpandWhitespace ); }}
case "Variable" -> append( (Element)n, bP, toExpandWhitespace );
default -> bP.append( textChildFlat( n )); }}
return Pattern.compile( bP.toString(), flags ); }
/** Offset within a variable interpolator of the first character of the variable name.
*/
static final int variableName = 2;
//// P r i v a t e ////////////////////////////////////////////////////////////////////////////////////
/** @param c The offset in `seq` at which to start appending.
*/
protected final void append( final CharSequence seq, int c, final StringBuilder b,
final boolean toExpandWhitespace ) {
final int cN = seq.length();
if( !toExpandWhitespace ) {
b.append( seq, c, cN );
return; }
final Matcher m = plainWhitespaceMatcher.reset( seq );
if( m.lookingAt() ) {
b.append( "(?: |\n|\r\n|\\x{A0})+" );
m.region( c = m.end(), cN ); }
while( m.find() ) {
b.append( seq, c, m.start() );
b.append( "(?: |\n|\r\n|\\x{A0})+" );
c = m.end(); }
if( c < cN ) b.append( seq, c, cN ); }
protected final void append( CharSequence seq, StringBuilder b, boolean toExpandWhitespace ) {
append( seq, 0, b, toExpandWhitespace ); }
/** Appends to `b` the value of `variable`, or throws `FailedInterpolation`.
*
* <p>The base implementation of this method recognizes no variables
* and simply throws `FailedInterpolation`.</p>
*
* @param variable The image of a variable interpolator.
*/
protected void append( final Element variable, final StringBuilder b,
final boolean toExpandWhitespace ) throws FailedInterpolation {
throw new FailedInterpolation( variable, variableName, "No such variable in this context" ); }
/** @param tF Flat text from the image of a regular-expression pattern.
* @param c The offset in `tF` at which to start vetting.
*/
private boolean hasNoMetacharacter( final String tF, int c ) {
final int cEnd = tF.length();
while( c < cEnd ) if( metacharacters.indexOf(tF.charAt(c++)) >= 0 ) return false;
return true; }
private final ImageMould<?> mould;
/** A pattern that `matches` in a regular-expression pattern a `\N{⋯}` element designating
* a character by its numeric code point. It captures as group (1) the code point.
*
* @see java.util.regex.Matcher#match()
* @see <a href='http://reluk.ca/project/Breccia/language_definition.brec.xht#n'>
* Breccia language definition § Pattern language, `\N{⋯}` element</a>
*/
private static final Pattern numberedCharacterBackslashPattern = Pattern.compile(
"\\\\N\\{ *U\\+(\\p{XDigit}+) *\\}" );
private final Matcher numberedCharacterBackslashMatcher =
numberedCharacterBackslashPattern.matcher( "" );
/** A pattern to `find` a sequence of plain whitespace.
*
* @see java.util.regex.Matcher#find()
*/
private static final Pattern plainWhitespacePattern = Pattern.compile( "(?: |\n|\r\n)+" );
private final Matcher plainWhitespaceMatcher = plainWhitespacePattern.matcher( "" );
private final StringBuilder stringBuilder = new StringBuilder(
/*initial capacity*/0x800 ); } // = 2048
// NOTES
// ─────
// MLM Multi-line mode operation of Breccian pattern matchers.
// http://reluk.ca/project/Breccia/language_definition.brec.xht#consistent,perl-s,multi-line
// http://reluk.ca/project/Breccia/language_definition.brec.xht#consistent,perl-s,multi-line:2
//
// NSC Presently ‘null in switch cases is a preview feature and is disabled by default’ (JDK 18),
// else this code could be simplified.
// Copyright © 2022-2024 Michael Allan. Licence MIT.