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server/node_modules/graphql/error/printError.js.flow

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+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ */
+
+import { getLocation } from '../language/location';
+import type { SourceLocation } from '../language/location';
+import type { Source } from '../language/source';
+import type { GraphQLError } from './GraphQLError';
+
+/**
+ * Prints a GraphQLError to a string, representing useful location information
+ * about the error's position in the source.
+ */
+export function printError(error: GraphQLError): string {
+  const printedLocations = [];
+  if (error.nodes) {
+    for (const node of error.nodes) {
+      if (node.loc) {
+        printedLocations.push(
+          highlightSourceAtLocation(
+            node.loc.source,
+            getLocation(node.loc.source, node.loc.start),
+          ),
+        );
+      }
+    }
+  } else if (error.source && error.locations) {
+    const source = error.source;
+    for (const location of error.locations) {
+      printedLocations.push(highlightSourceAtLocation(source, location));
+    }
+  }
+  return printedLocations.length === 0
+    ? error.message
+    : [error.message, ...printedLocations].join('\n\n') + '\n';
+}
+
+/**
+ * Render a helpful description of the location of the error in the GraphQL
+ * Source document.
+ */
+function highlightSourceAtLocation(
+  source: Source,
+  location: SourceLocation,
+): string {
+  const firstLineColumnOffset = source.locationOffset.column - 1;
+  const body = whitespace(firstLineColumnOffset) + source.body;
+
+  const lineIndex = location.line - 1;
+  const lineOffset = source.locationOffset.line - 1;
+  const lineNum = location.line + lineOffset;
+
+  const columnOffset = location.line === 1 ? firstLineColumnOffset : 0;
+  const columnNum = location.column + columnOffset;
+
+  const lines = body.split(/\r\n|[\n\r]/g);
+  return (
+    `${source.name} (${lineNum}:${columnNum})\n` +
+    printPrefixedLines([
+      // Lines specified like this: ["prefix", "string"],
+      [`${lineNum - 1}: `, lines[lineIndex - 1]],
+      [`${lineNum}: `, lines[lineIndex]],
+      ['', whitespace(columnNum - 1) + '^'],
+      [`${lineNum + 1}: `, lines[lineIndex + 1]],
+    ])
+  );
+}
+
+function printPrefixedLines(lines: Array<[string, string]>): string {
+  const existingLines = lines.filter(([_, line]) => line !== undefined);
+
+  let padLen = 0;
+  for (const [prefix] of existingLines) {
+    padLen = Math.max(padLen, prefix.length);
+  }
+
+  return existingLines
+    .map(([prefix, line]) => lpad(padLen, prefix) + line)
+    .join('\n');
+}
+
+function whitespace(len: number): string {
+  return Array(len + 1).join(' ');
+}
+
+function lpad(len: number, str: string): string {
+  return whitespace(len - str.length) + str;
+}