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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
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
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package com.oracle.truffle.js.nodes.cast;

import java.math.BigInteger;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.nodes.SlowPathException;
import com.oracle.truffle.api.profiles.ConditionProfile;
import com.oracle.truffle.js.nodes.JSNodeUtil;
import com.oracle.truffle.js.nodes.JavaScriptBaseNode;
import com.oracle.truffle.js.runtime.JSRuntime;

This implements ECMA 9.3.1 ToNumber applied to the String Type.
/**
 * This implements ECMA 9.3.1 ToNumber applied to the String Type.
 *
 */
public abstract class JSStringToNumberNode extends JavaScriptBaseNode {

    static final int PREFIX_LENGTH = 2;
    static final int SAFE_HEX_DIGITS = PREFIX_LENGTH + 13;
    static final int SAFE_OCTAL_DIGITS = PREFIX_LENGTH + 17;
    static final int SAFE_BINARY_DIGITS = PREFIX_LENGTH + 53;

    
Sign + at most 16 digits, i.e. Number.MIN_SAFE_INTEGER.toString().length. /** Sign + at most 16 digits, i.e. {@code Number.MIN_SAFE_INTEGER.toString().length}. */
    static final int MAX_SAFE_INTEGER_LENGTH = 17;
    static final int SMALL_INT_LENGTH = 9;

    @Child private JSTrimWhitespaceNode trimWhitespaceNode;

    public final double executeString(String input) {
        if (trimWhitespaceNode == null) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            trimWhitespaceNode = insert(JSTrimWhitespaceNode.create());
        }
        return executeNoTrim(trimWhitespaceNode.executeString(input));
    }

    protected abstract double executeNoTrim(String input);

    public static JSStringToNumberNode create() {
        return JSStringToNumberNodeGen.create();
    }

    protected static final boolean startsWithI(String input) {
        return input.length() >= JSRuntime.INFINITY_STRING.length() && input.length() <= (JSRuntime.INFINITY_STRING.length() + 1) && (input.charAt(0) == 'I' || input.charAt(1) == 'I');
    }

    
First two chars are valid finite double. Implies !startsWithI && !isHex && !isOctal && !isBinary. /**
     * First two chars are valid finite double. Implies
     * {@code !startsWithI && !isHex && !isOctal && !isBinary}.
     */
    protected static final boolean startsWithValidDouble(String input) {
        char firstChar = input.charAt(0);
        if (JSRuntime.isAsciiDigit(firstChar) || firstChar == '-' || firstChar == '.' || firstChar == '+') {
            if (input.length() >= 2) {
                char secondChar = input.charAt(1);
                return JSRuntime.isAsciiDigit(secondChar) || secondChar == '.' || secondChar == 'e' || secondChar == 'E';
            } else {
                return true;
            }
        } else {
            return false;
        }
    }

    protected static final boolean startsWithValidInt(String input) {
        char firstChar = input.charAt(0);
        return (JSRuntime.isAsciiDigit(firstChar) || firstChar == '-' || firstChar == '+') && (input.length() < 2 || JSRuntime.isAsciiDigit(input.charAt(1)));
    }

    protected static final boolean allDigits(String input, int maxLength) {
        assert input.length() <= maxLength;
        for (int i = 0; i < maxLength; i++) {
            if (i >= input.length()) {
                return true;
            } else if (!JSRuntime.isAsciiDigit(input.charAt(i))) {
                return false;
            }
        }
        return false;
    }

    protected static final boolean isHex(String input) {
        return input.length() >= 2 && input.charAt(0) == '0' && (input.charAt(1) == 'x' || input.charAt(1) == 'X');
    }

    protected static final boolean isOctal(String input) {
        return input.length() >= 2 && input.charAt(0) == '0' && (input.charAt(1) == 'o' || input.charAt(1) == 'O');
    }

    protected static final boolean isBinary(String input) {
        return input.length() >= 2 && input.charAt(0) == '0' && (input.charAt(1) == 'b' || input.charAt(1) == 'B');
    }

    @Specialization(guards = "input.length() == 0")
    protected double doLengthIsZero(@SuppressWarnings("unused") String input) {
        return 0;
    }

    @Specialization(guards = "startsWithI(input)")
    protected double doInfinity(String input,
                    @Cached("createBinaryProfile()") ConditionProfile endsWithInfinity) {
        if (endsWithInfinity.profile(input.endsWith(JSRuntime.INFINITY_STRING))) {
            return JSRuntime.identifyInfinity(input, input.charAt(0));
        } else {
            return Double.NaN;
        }
    }

    @Specialization(guards = {"input.length() > 0", "!startsWithI(input)", "!startsWithValidDouble(input)", "!isHex(input)", "!isOctal(input)", "!isBinary(input)"})
    protected double doNaN(@SuppressWarnings("unused") String input) {
        return Double.NaN;
    }

    @Specialization(guards = {"isHex(input)", "input.length() <= SAFE_HEX_DIGITS"})
    @TruffleBoundary
    protected double doHexSafe(String input) {
        return safeIntegerToDouble(JSRuntime.parseSafeInteger(input, 2, input.length(), 16));
    }

    @Specialization(guards = {"isHex(input)", "input.length() > SAFE_HEX_DIGITS"})
    @TruffleBoundary
    protected double doHex(String input) {
        try {
            return new BigInteger(input.substring(2), 16).doubleValue();
        } catch (NumberFormatException ex) {
            return Double.NaN;
        }
    }

    @Specialization(guards = {"isOctal(input)", "input.length() <= SAFE_OCTAL_DIGITS"})
    @TruffleBoundary
    protected double doOctalSafe(String input) {
        return safeIntegerToDouble(JSRuntime.parseSafeInteger(input, 2, input.length(), 8));
    }

    @Specialization(guards = {"isOctal(input)", "input.length() > SAFE_OCTAL_DIGITS"})
    @TruffleBoundary
    protected double doOctal(String input) {
        try {
            return new BigInteger(input.substring(2), 8).doubleValue();
        } catch (NumberFormatException ex) {
            return Double.NaN;
        }
    }

    @Specialization(guards = {"isBinary(input)", "input.length() <= SAFE_BINARY_DIGITS"})
    @TruffleBoundary
    protected double doBinarySafe(String input) {
        return safeIntegerToDouble(JSRuntime.parseSafeInteger(input, 2, input.length(), 2));
    }

    @Specialization(guards = {"isBinary(input)", "input.length() > SAFE_BINARY_DIGITS"})
    @TruffleBoundary
    protected double doBinary(String input) {
        try {
            return new BigInteger(input.substring(2), 2).doubleValue();
        } catch (NumberFormatException ex) {
            return Double.NaN;
        }
    }

    @Specialization(guards = {"input.length() > 0", "input.length() <= SMALL_INT_LENGTH", "allDigits(input, SMALL_INT_LENGTH)"})
    protected double doSmallPosInt(String input) {
        int result = 0;
        int pos = 0;
        int len = input.length();
        while (pos < len) {
            char c = input.charAt(pos);
            assert JSRuntime.isAsciiDigit(c);
            result *= 10;
            result += c - '0';
            pos++;
        }
        assert result >= 0 && checkLongResult(result, input);
        return result;
    }

    @Specialization(guards = {"input.length() > 0", "input.length() <= MAX_SAFE_INTEGER_LENGTH", "startsWithValidInt(input)"}, rewriteOn = SlowPathException.class, replaces = "doSmallPosInt")
    protected double doInteger(String input) throws SlowPathException {
        long result = JSRuntime.parseSafeInteger(input);
        if (result == JSRuntime.INVALID_SAFE_INTEGER) {
            throw JSNodeUtil.slowPathException();
        }
        assert checkLongResult(result, input);
        return result;
    }

    @TruffleBoundary
    @Specialization(guards = {"input.length() > 0", "startsWithValidDouble(input)"}, replaces = "doInteger")
    protected double doDouble(String input) {
        return JSRuntime.parseDoubleOrNaN(input);
    }

    private static double safeIntegerToDouble(long result) {
        if (result == JSRuntime.INVALID_SAFE_INTEGER) {
            return Double.NaN;
        }
        assert JSRuntime.isSafeInteger(result);
        return result;
    }

    @TruffleBoundary
    private static boolean checkLongResult(long result, String input) {
        return Double.compare(result, JSRuntime.parseDoubleOrNaN(input)) == 0;
    }
}