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qwen/nodejs/node_modules/istanbul-lib-source-maps/lib/get-mapping.js

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+/*
+ Copyright 2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+'use strict';
+
+const pathutils = require('./pathutils');
+const {
+    GREATEST_LOWER_BOUND,
+    LEAST_UPPER_BOUND
+} = require('source-map').SourceMapConsumer;
+
+/**
+ * AST ranges are inclusive for start positions and exclusive for end positions.
+ * Source maps are also logically ranges over text, though interacting with
+ * them is generally achieved by working with explicit positions.
+ *
+ * When finding the _end_ location of an AST item, the range behavior is
+ * important because what we're asking for is the _end_ of whatever range
+ * corresponds to the end location we seek.
+ *
+ * This boils down to the following steps, conceptually, though the source-map
+ * library doesn't expose primitives to do this nicely:
+ *
+ * 1. Find the range on the generated file that ends at, or exclusively
+ *    contains the end position of the AST node.
+ * 2. Find the range on the original file that corresponds to
+ *    that generated range.
+ * 3. Find the _end_ location of that original range.
+ */
+function originalEndPositionFor(sourceMap, generatedEnd) {
+    // Given the generated location, find the original location of the mapping
+    // that corresponds to a range on the generated file that overlaps the
+    // generated file end location. Note however that this position on its
+    // own is not useful because it is the position of the _start_ of the range
+    // on the original file, and we want the _end_ of the range.
+    const beforeEndMapping = originalPositionTryBoth(
+        sourceMap,
+        generatedEnd.line,
+        generatedEnd.column - 1
+    );
+    if (beforeEndMapping.source === null) {
+        return null;
+    }
+
+    // Convert that original position back to a generated one, with a bump
+    // to the right, and a rightward bias. Since 'generatedPositionFor' searches
+    // for mappings in the original-order sorted list, this will find the
+    // mapping that corresponds to the one immediately after the
+    // beforeEndMapping mapping.
+    const afterEndMapping = sourceMap.generatedPositionFor({
+        source: beforeEndMapping.source,
+        line: beforeEndMapping.line,
+        column: beforeEndMapping.column + 1,
+        bias: LEAST_UPPER_BOUND
+    });
+    if (
+        // If this is null, it means that we've hit the end of the file,
+        // so we can use Infinity as the end column.
+        afterEndMapping.line === null ||
+        // If these don't match, it means that the call to
+        // 'generatedPositionFor' didn't find any other original mappings on
+        // the line we gave, so consider the binding to extend to infinity.
+        sourceMap.originalPositionFor(afterEndMapping).line !==
+            beforeEndMapping.line
+    ) {
+        return {
+            source: beforeEndMapping.source,
+            line: beforeEndMapping.line,
+            column: Infinity
+        };
+    }
+
+    // Convert the end mapping into the real original position.
+    return sourceMap.originalPositionFor(afterEndMapping);
+}
+
+/**
+ * Attempts to determine the original source position, first
+ * returning the closest element to the left (GREATEST_LOWER_BOUND),
+ * and next returning the closest element to the right (LEAST_UPPER_BOUND).
+ */
+function originalPositionTryBoth(sourceMap, line, column) {
+    const mapping = sourceMap.originalPositionFor({
+        line,
+        column,
+        bias: GREATEST_LOWER_BOUND
+    });
+    if (mapping.source === null) {
+        return sourceMap.originalPositionFor({
+            line,
+            column,
+            bias: LEAST_UPPER_BOUND
+        });
+    } else {
+        return mapping;
+    }
+}
+
+function isInvalidPosition(pos) {
+    return (
+        !pos ||
+        typeof pos.line !== 'number' ||
+        typeof pos.column !== 'number' ||
+        pos.line < 0 ||
+        pos.column < 0
+    );
+}
+
+/**
+ * determines the original position for a given location
+ * @param  {SourceMapConsumer} sourceMap the source map
+ * @param  {Object} generatedLocation the original location Object
+ * @returns {Object} the remapped location Object
+ */
+function getMapping(sourceMap, generatedLocation, origFile) {
+    if (!generatedLocation) {
+        return null;
+    }
+
+    if (
+        isInvalidPosition(generatedLocation.start) ||
+        isInvalidPosition(generatedLocation.end)
+    ) {
+        return null;
+    }
+
+    const start = originalPositionTryBoth(
+        sourceMap,
+        generatedLocation.start.line,
+        generatedLocation.start.column
+    );
+    let end = originalEndPositionFor(sourceMap, generatedLocation.end);
+
+    /* istanbul ignore if: edge case too hard to test for */
+    if (!(start && end)) {
+        return null;
+    }
+
+    if (!(start.source && end.source)) {
+        return null;
+    }
+
+    if (start.source !== end.source) {
+        return null;
+    }
+
+    /* istanbul ignore if: edge case too hard to test for */
+    if (start.line === null || start.column === null) {
+        return null;
+    }
+
+    /* istanbul ignore if: edge case too hard to test for */
+    if (end.line === null || end.column === null) {
+        return null;
+    }
+
+    if (start.line === end.line && start.column === end.column) {
+        end = sourceMap.originalPositionFor({
+            line: generatedLocation.end.line,
+            column: generatedLocation.end.column,
+            bias: LEAST_UPPER_BOUND
+        });
+        end.column -= 1;
+    }
+
+    return {
+        source: pathutils.relativeTo(start.source, origFile),
+        loc: {
+            start: {
+                line: start.line,
+                column: start.column
+            },
+            end: {
+                line: end.line,
+                column: end.column
+            }
+        }
+    };
+}
+
+module.exports = getMapping;