commonMain.androidx.compose.foundation.text.ValidatingOffsetMapping.kt Maven / Gradle / Ivy

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Higher level abstractions of the Compose UI primitives. This library is design system agnostic, providing the high-level building blocks for both application and design-system developers

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/*
 * Copyright 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.compose.foundation.text

import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.input.OffsetMapping
import androidx.compose.ui.text.input.TransformedText
import androidx.compose.ui.text.input.VisualTransformation

internal val ValidatingEmptyOffsetMappingIdentity: OffsetMapping = ValidatingOffsetMapping(
    delegate = OffsetMapping.Identity,
    originalLength = 0,
    transformedLength = 0
)

internal fun VisualTransformation.filterWithValidation(text: AnnotatedString): TransformedText {
    return filter(text).let { transformed ->
        TransformedText(
            transformed.text,
            ValidatingOffsetMapping(
                delegate = transformed.offsetMapping,
                originalLength = text.length,
                transformedLength = transformed.text.length
            )
        )
    }
}

private class ValidatingOffsetMapping(
    private val delegate: OffsetMapping,
    private val originalLength: Int,
    private val transformedLength: Int
) : OffsetMapping {

    /**
     * Calls [originalToTransformed][OffsetMapping.originalToTransformed] and throws a detailed
     * exception if the returned value is outside the range of indices [0, [transformedLength]].
     */
    override fun originalToTransformed(offset: Int): Int {
        return delegate.originalToTransformed(offset).also { transformedOffset ->
            check(transformedOffset in 0..transformedLength) {
                "OffsetMapping.originalToTransformed returned invalid mapping: " +
                    "$offset -> $transformedOffset is not in range of transformed text " +
                    "[0, $transformedLength]"
            }
        }
    }

    /**
     * Calls [transformedToOriginal][OffsetMapping.transformedToOriginal] and throws a detailed
     * exception if the returned value is outside the range of indices [0, [originalLength]].
     */
    override fun transformedToOriginal(offset: Int): Int {
        return delegate.transformedToOriginal(offset).also { originalOffset ->
            check(originalOffset in 0..originalLength) {
                "OffsetMapping.transformedToOriginal returned invalid mapping: " +
                    "$offset -> $originalOffset is not in range of original text " +
                    "[0, $originalLength]"
            }
        }
    }
}