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 * The Universal Permissive License (UPL), Version 1.0
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
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 * minimum a reference to the UPL must be included in all copies or substantial
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package com.oracle.graal.python.builtins.objects.str;

import java.util.Objects;

import com.oracle.graal.python.PythonLanguage;
import com.oracle.graal.python.builtins.objects.cext.capi.CExtNodes.PCallCapiFunction;
import com.oracle.graal.python.builtins.objects.cext.common.CExtCommonNodesFactory.UnicodeFromWcharNodeGen;
import com.oracle.graal.python.builtins.objects.str.StringNodes.StringMaterializeNode;
import com.oracle.graal.python.nodes.util.CastToJavaIntExactNode;
import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.TruffleLogger;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.interop.UnsupportedMessageException;

public final class NativeCharSequence implements CharSequence {
    private static final TruffleLogger LOGGER = PythonLanguage.getLogger(NativeCharSequence.class);

    /**
     * Pointer to the native buffer (most like a {@code char*} containing ASCII characters but could
     * also be an arbitrary {@code void*} for {@code Py_UCS1}, {@code Py_UCS2}, or {@code Py_UCS4}
     * characters)
     */
    private final Object ptr;

    /**
     * The size of a single character in bytes (valid values are {@code 1, 2, 4}).
     */
    private final int elementSize;

    /**
     * Specifies if the native buffer contains only ASCII characters.
     */
    private final boolean asciiOnly;

    private String materialized;

    public NativeCharSequence(Object ptr, int elementSize, boolean asciiOnly) {
        assert elementSize == 1 || elementSize == 2 || elementSize == 4;
        this.ptr = ptr;
        this.elementSize = elementSize;
        this.asciiOnly = asciiOnly;
    }

    @Override
    public int length() {
        return materialize().length();
    }

    int length(InteropLibrary lib, CastToJavaIntExactNode castToJavaIntNode) {
        try {
            int arraySize = castToJavaIntNode.execute(lib.getArraySize(ptr));
            assert arraySize % elementSize == 0;
            // we need to subtract the terminating null character
            return arraySize / elementSize;
        } catch (UnsupportedMessageException e) {
            throw CompilerDirectives.shouldNotReachHere("pointer of NativeCharSequence is not an array");
        }
    }

    @Override
    public char charAt(int index) {
        return materialize().charAt(index);
    }

    @Override
    public CharSequence subSequence(int start, int end) {
        return materialize().subSequence(start, end);
    }

    boolean isMaterialized() {
        return materialized != null;
    }

    String getMaterialized() {
        return materialized;
    }

    private String materialize() {
        if (!isMaterialized()) {
            LOGGER.warning("uncached materialization of NativeCharSequence");
            materialized = StringMaterializeNode.materializeNativeCharSequence(this, PCallCapiFunction.getUncached(), UnicodeFromWcharNodeGen.getUncached());
        }
        return materialized;
    }

    public Object getPtr() {
        return ptr;
    }

    public int getElementSize() {
        return elementSize;
    }

    public boolean isAsciiOnly() {
        return asciiOnly;
    }

    @Override
    public String toString() {
        CompilerAsserts.neverPartOfCompilation();
        if (isMaterialized()) {
            return materialized;
        }
        return Objects.toString(ptr);
    }
}
