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package com.oracle.truffle.regex;

import java.util.Collections;
import java.util.Map;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.regex.tregex.TRegexOptions;
import com.oracle.truffle.regex.util.CompilationResult;
import com.oracle.truffle.regex.util.LRUCache;

public class CachingRegexEngine extends RegexEngine {

    private final Map<RegexSource, CompilationResult<RegexObject>> cache = Collections.synchronizedMap(new LRUCache<>(TRegexOptions.RegexMaxCacheSize));

    public CachingRegexEngine(RegexCompiler compiler, RegexOptions options) {
        super(compiler, options);
    }

    @Override
    public RegexObject compile(RegexSource regexSource) throws RegexSyntaxException, UnsupportedRegexException {
        CompilationResult<RegexObject> result = cacheGet(regexSource);
        if (result == null) {
            result = doCompile(regexSource);
            cachePut(regexSource, result);
        }
        return result.unpack();
    }

    private CompilationResult<RegexObject> doCompile(RegexSource regexSource) {
        return CompilationResult.pack(() -> super.compile(regexSource));
    }

    @TruffleBoundary
    private CompilationResult<RegexObject> cacheGet(RegexSource source) {
        return cache.get(source);
    }

    @TruffleBoundary
    private CompilationResult<RegexObject> cachePut(RegexSource source, CompilationResult<RegexObject> result) {
        return cache.put(source, result);
    }
}