Examples with Description io.prestosql.spi.function.Description used on opensource projects

Example 31 with Description

use of io.prestosql.spi.function.Description in project hetu-core by openlookeng.

the class StringFunctions method replace.

@Description("greedily replaces occurrences of a pattern with a string")
@ScalarFunction
@LiteralParameters({ "x", "y", "z", "u" })
@Constraint(variable = "u", expression = "min(2147483647, x + z * (x + 1))")
@SqlType("varchar(u)")
public static Slice replace(@SqlType("varchar(x)") Slice str, @SqlType("varchar(y)") Slice search, @SqlType("varchar(z)") Slice replace) {
    // Empty search?
    if (search.length() == 0) {
        // With empty `search` we insert `replace` in front of every character and and the end
        Slice buffer = Slices.allocate((countCodePoints(str) + 1) * replace.length() + str.length());
        // Always start with replace
        buffer.setBytes(0, replace);
        int indexBuffer = replace.length();
        // After every code point insert `replace`
        int index = 0;
        while (index < str.length()) {
            int codePointLength = lengthOfCodePointSafe(str, index);
            // Append current code point
            buffer.setBytes(indexBuffer, str, index, codePointLength);
            indexBuffer += codePointLength;
            // Append `replace`
            buffer.setBytes(indexBuffer, replace);
            indexBuffer += replace.length();
            // Advance pointer to current code point
            index += codePointLength;
        }
        return buffer;
    }
    // Allocate a reasonable buffer
    Slice buffer = Slices.allocate(str.length());
    int index = 0;
    int indexBuffer = 0;
    while (index < str.length()) {
        int matchIndex = str.indexOf(search, index);
        // Found a match?
        if (matchIndex < 0) {
            // No match found so copy the rest of string
            int bytesToCopy = str.length() - index;
            buffer = Slices.ensureSize(buffer, indexBuffer + bytesToCopy);
            buffer.setBytes(indexBuffer, str, index, bytesToCopy);
            indexBuffer += bytesToCopy;
            break;
        }
        int bytesToCopy = matchIndex - index;
        buffer = Slices.ensureSize(buffer, indexBuffer + bytesToCopy + replace.length());
        // Non empty match?
        if (bytesToCopy > 0) {
            buffer.setBytes(indexBuffer, str, index, bytesToCopy);
            indexBuffer += bytesToCopy;
        }
        // Non empty replace?
        if (replace.length() > 0) {
            buffer.setBytes(indexBuffer, replace);
            indexBuffer += replace.length();
        }
        // Continue searching after match
        index = matchIndex + search.length();
    }
    return buffer.slice(0, indexBuffer);
}

Example 32 with Description

use of io.prestosql.spi.function.Description in project hetu-core by openlookeng.

the class StringFunctions method splitPart.

@SqlNullable
@Description("splits a string by a delimiter and returns the specified field (counting from one)")
@ScalarFunction
@LiteralParameters({ "x", "y" })
@SqlType("varchar(x)")
public static Slice splitPart(@SqlType("varchar(x)") Slice string, @SqlType("varchar(y)") Slice delimiter, @SqlType(StandardTypes.BIGINT) long index) {
    checkCondition(index > 0, INVALID_FUNCTION_ARGUMENT, "Index must be greater than zero");
    // Empty delimiter? Then every character will be a split
    if (delimiter.length() == 0) {
        int startCodePoint = toIntExact(index);
        int indexStart = offsetOfCodePoint(string, startCodePoint - 1);
        if (indexStart < 0) {
            // index too big
            return null;
        }
        int length = lengthOfCodePoint(string, indexStart);
        if (indexStart + length > string.length()) {
            throw new PrestoException(INVALID_FUNCTION_ARGUMENT, "Invalid UTF-8 encoding");
        }
        return string.slice(indexStart, length);
    }
    int matchCount = 0;
    int previousIndex = 0;
    while (previousIndex < string.length()) {
        int matchIndex = string.indexOf(delimiter, previousIndex);
        // No match
        if (matchIndex < 0) {
            break;
        }
        // Reached the requested part?
        if (++matchCount == index) {
            return string.slice(previousIndex, matchIndex - previousIndex);
        }
        // Continue searching after the delimiter
        previousIndex = matchIndex + delimiter.length();
    }
    if (matchCount == index - 1) {
        // returns last section of the split
        return string.slice(previousIndex, string.length() - previousIndex);
    }
    // index is too big, null is returned
    return null;
}

Example 33 with Description

use of io.prestosql.spi.function.Description in project hetu-core by openlookeng.

the class StringFunctions method levenshteinDistance.

@Description("computes Levenshtein distance between two strings")
@ScalarFunction
@LiteralParameters({ "x", "y" })
@SqlType(StandardTypes.BIGINT)
public static long levenshteinDistance(@SqlType("varchar(x)") Slice left, @SqlType("varchar(y)") Slice right) {
    int[] leftCodePoints = castToCodePoints(left);
    int[] rightCodePoints = castToCodePoints(right);
    if (leftCodePoints.length < rightCodePoints.length) {
        int[] tempCodePoints = leftCodePoints;
        leftCodePoints = rightCodePoints;
        rightCodePoints = tempCodePoints;
    }
    if (rightCodePoints.length == 0) {
        return leftCodePoints.length;
    }
    checkCondition((leftCodePoints.length * (rightCodePoints.length - 1)) <= 1_000_000, INVALID_FUNCTION_ARGUMENT, "The combined inputs for Levenshtein distance are too large");
    int[] distances = new int[rightCodePoints.length];
    for (int i = 0; i < rightCodePoints.length; i++) {
        distances[i] = i + 1;
    }
    for (int i = 0; i < leftCodePoints.length; i++) {
        int leftUpDistance = distances[0];
        if (leftCodePoints[i] == rightCodePoints[0]) {
            distances[0] = i;
        } else {
            distances[0] = Math.min(i, distances[0]) + 1;
        }
        for (int j = 1; j < rightCodePoints.length; j++) {
            int leftUpDistanceNext = distances[j];
            if (leftCodePoints[i] == rightCodePoints[j]) {
                distances[j] = leftUpDistance;
            } else {
                distances[j] = Math.min(distances[j - 1], Math.min(leftUpDistance, distances[j])) + 1;
            }
            leftUpDistance = leftUpDistanceNext;
        }
    }
    return distances[rightCodePoints.length - 1];
}

Example 34 with Description

use of io.prestosql.spi.function.Description in project hetu-core by openlookeng.

the class VarbinaryFunctions method toIEEE754Binary32.

@Description("encode value as a big endian varbinary according to IEEE 754 single-precision floating-point format")
@ScalarFunction("to_ieee754_32")
@SqlType(StandardTypes.VARBINARY)
public static Slice toIEEE754Binary32(@SqlType(StandardTypes.REAL) long value) {
    Slice slice = Slices.allocate(Float.BYTES);
    slice.setInt(0, Integer.reverseBytes((int) value));
    return slice;
}

Example 35 with Description

use of io.prestosql.spi.function.Description in project hetu-core by openlookeng.

the class VarbinaryFunctions method toBigEndian32.

@Description("encode value as a 32-bit 2's complement big endian varbinary")
@ScalarFunction("to_big_endian_32")
@SqlType(StandardTypes.VARBINARY)
public static Slice toBigEndian32(@SqlType(StandardTypes.INTEGER) long value) {
    Slice slice = Slices.allocate(Integer.BYTES);
    slice.setInt(0, Integer.reverseBytes((int) value));
    return slice;
}