prettier/src/util.js

"use strict";

function isExportDeclaration(node) {
  if (node) {
    switch (node.type) {
      case "ExportDeclaration":
      case "ExportDefaultDeclaration":
      case "ExportDefaultSpecifier":
      case "DeclareExportDeclaration":
      case "ExportNamedDeclaration":
      case "ExportAllDeclaration":
        return true;
    }
  }

  return false;
}

function getParentExportDeclaration(path) {
  const parentNode = path.getParentNode();
  if (path.getName() === "declaration" && isExportDeclaration(parentNode)) {
    return parentNode;
  }

  return null;
}

function getPenultimate(arr) {
  if (arr.length > 1) {
    return arr[arr.length - 2];
  }
  return null;
}

function getLast(arr) {
  if (arr.length > 0) {
    return arr[arr.length - 1];
  }
  return null;
}

function skip(chars) {
  return (text, index, opts) => {
    const backwards = opts && opts.backwards;

    // Allow `skip` functions to be threaded together without having
    // to check for failures (did someone say monads?).
    if (index === false) {
      return false;
    }

    const length = text.length;
    let cursor = index;
    while (cursor >= 0 && cursor < length) {
      const c = text.charAt(cursor);
      if (chars instanceof RegExp) {
        if (!chars.test(c)) {
          return cursor;
        }
      } else if (chars.indexOf(c) === -1) {
        return cursor;
      }

      backwards ? cursor-- : cursor++;
    }

    if (cursor === -1 || cursor === length) {
      // If we reached the beginning or end of the file, return the
      // out-of-bounds cursor. It's up to the caller to handle this
      // correctly. We don't want to indicate `false` though if it
      // actually skipped valid characters.
      return cursor;
    }
    return false;
  };
}

const skipWhitespace = skip(/\s/);
const skipSpaces = skip(" \t");
const skipToLineEnd = skip(",; \t");
const skipEverythingButNewLine = skip(/[^\r\n]/);

function skipInlineComment(text, index) {
  if (index === false) {
    return false;
  }

  if (text.charAt(index) === "/" && text.charAt(index + 1) === "*") {
    for (let i = index + 2; i < text.length; ++i) {
      if (text.charAt(i) === "*" && text.charAt(i + 1) === "/") {
        return i + 2;
      }
    }
  }
  return index;
}

function skipTrailingComment(text, index) {
  if (index === false) {
    return false;
  }

  if (text.charAt(index) === "/" && text.charAt(index + 1) === "/") {
    return skipEverythingButNewLine(text, index);
  }
  return index;
}

// This one doesn't use the above helper function because it wants to
// test \r\n in order and `skip` doesn't support ordering and we only
// want to skip one newline. It's simple to implement.
function skipNewline(text, index, opts) {
  const backwards = opts && opts.backwards;
  if (index === false) {
    return false;
  }

  const atIndex = text.charAt(index);
  if (backwards) {
    if (text.charAt(index - 1) === "\r" && atIndex === "\n") {
      return index - 2;
    }
    if (
      atIndex === "\n" ||
      atIndex === "\r" ||
      atIndex === "\u2028" ||
      atIndex === "\u2029"
    ) {
      return index - 1;
    }
  } else {
    if (atIndex === "\r" && text.charAt(index + 1) === "\n") {
      return index + 2;
    }
    if (
      atIndex === "\n" ||
      atIndex === "\r" ||
      atIndex === "\u2028" ||
      atIndex === "\u2029"
    ) {
      return index + 1;
    }
  }

  return index;
}

function hasNewline(text, index, opts) {
  opts = opts || {};
  const idx = skipSpaces(text, opts.backwards ? index - 1 : index, opts);
  const idx2 = skipNewline(text, idx, opts);
  return idx !== idx2;
}

function hasNewlineInRange(text, start, end) {
  for (let i = start; i < end; ++i) {
    if (text.charAt(i) === "\n") {
      return true;
    }
  }
  return false;
}

// Note: this function doesn't ignore leading comments unlike isNextLineEmpty
function isPreviousLineEmpty(text, node) {
  let idx = locStart(node) - 1;
  idx = skipSpaces(text, idx, { backwards: true });
  idx = skipNewline(text, idx, { backwards: true });
  idx = skipSpaces(text, idx, { backwards: true });
  const idx2 = skipNewline(text, idx, { backwards: true });
  return idx !== idx2;
}

function isNextLineEmpty(text, node) {
  let oldIdx = null;
  let idx = locEnd(node);
  while (idx !== oldIdx) {
    // We need to skip all the potential trailing inline comments
    oldIdx = idx;
    idx = skipToLineEnd(text, idx);
    idx = skipInlineComment(text, idx);
    idx = skipSpaces(text, idx);
  }
  idx = skipTrailingComment(text, idx);
  idx = skipNewline(text, idx);
  return hasNewline(text, idx);
}

function getNextNonSpaceNonCommentCharacter(text, node) {
  let oldIdx = null;
  let idx = locEnd(node);
  while (idx !== oldIdx) {
    oldIdx = idx;
    idx = skipSpaces(text, idx);
    idx = skipInlineComment(text, idx);
    idx = skipTrailingComment(text, idx);
    idx = skipNewline(text, idx);
  }
  return text.charAt(idx);
}

function hasSpaces(text, index, opts) {
  opts = opts || {};
  const idx = skipSpaces(text, opts.backwards ? index - 1 : index, opts);
  return idx !== index;
}

function locStart(node) {
  if (node.decorators && node.decorators.length > 0) {
    return locStart(node.decorators[0]);
  }
  if (node.range) {
    return node.range[0];
  }
  if (typeof node.start === "number") {
    return node.start;
  }
  if (node.source) {
    return lineColumnToIndex(node.source.start, node.source.input.css) - 1;
  }
}

function locEnd(node) {
  if (node.range) {
    return node.range[1];
  }
  if (typeof node.end === "number") {
    return node.end;
  }
  if (node.source) {
    return lineColumnToIndex(node.source.end, node.source.input.css);
  }
}

// Super inefficient, needs to be cached.
function lineColumnToIndex(lineColumn, text) {
  let index = 0;
  for (let i = 0; i < lineColumn.line - 1; ++i) {
    index = text.indexOf("\n", index) + 1;
    if (index === -1) {
      return -1;
    }
  }
  return index + lineColumn.column;
}

function setLocStart(node, index) {
  if (node.range) {
    node.range[0] = index;
  } else {
    node.start = index;
  }
}

function setLocEnd(node, index) {
  if (node.range) {
    node.range[1] = index;
  } else {
    node.end = index;
  }
}

const PRECEDENCE = {};
[
  ["||"],
  ["&&"],
  ["|"],
  ["^"],
  ["&"],
  ["==", "===", "!=", "!=="],
  ["<", ">", "<=", ">=", "in", "instanceof"],
  [">>", "<<", ">>>"],
  ["+", "-"],
  ["*", "/", "%"],
  ["**"]
].forEach((tier, i) => {
  tier.forEach(op => {
    PRECEDENCE[op] = i;
  });
});

function getPrecedence(op) {
  return PRECEDENCE[op];
}

// Tests if an expression starts with `{`, or (if forbidFunctionAndClass holds) `function` or `class`.
// Will be overzealous if there's already necessary grouping parentheses.
function startsWithNoLookaheadToken(node, forbidFunctionAndClass) {
  node = getLeftMost(node);
  switch (node.type) {
    case "FunctionExpression":
    case "ClassExpression":
      return forbidFunctionAndClass;
    case "ObjectExpression":
      return true;
    case "MemberExpression":
      return startsWithNoLookaheadToken(node.object, forbidFunctionAndClass);
    case "TaggedTemplateExpression":
      if (node.tag.type === "FunctionExpression") {
        // IIFEs are always already parenthesized
        return false;
      }
      return startsWithNoLookaheadToken(node.tag, forbidFunctionAndClass);
    case "CallExpression":
      if (node.callee.type === "FunctionExpression") {
        // IIFEs are always already parenthesized
        return false;
      }
      return startsWithNoLookaheadToken(node.callee, forbidFunctionAndClass);
    case "ConditionalExpression":
      return startsWithNoLookaheadToken(node.test, forbidFunctionAndClass);
    case "UpdateExpression":
      return (
        !node.prefix &&
        startsWithNoLookaheadToken(node.argument, forbidFunctionAndClass)
      );
    case "BindExpression":
      return (
        node.object &&
        startsWithNoLookaheadToken(node.object, forbidFunctionAndClass)
      );
    case "SequenceExpression":
      return startsWithNoLookaheadToken(
        node.expressions[0],
        forbidFunctionAndClass
      );
    default:
      return false;
  }
}

function getLeftMost(node) {
  if (node.left) {
    return getLeftMost(node.left);
  } else {
    return node;
  }
}

function hasBlockComments(node) {
  return node.comments && node.comments.some(isBlockComment);
}

function isBlockComment(comment) {
  return comment.type === "Block" || comment.type === "CommentBlock";
}

function getAlignmentSize(value, tabWidth, startIndex) {
  startIndex = startIndex || 0;

  let size = 0;
  for (let i = startIndex; i < value.length; ++i) {
    if (value[i] === "\t") {
      // Tabs behave in a way that they are aligned to the nearest
      // multiple of tabWidth:
      // 0 -> 4, 1 -> 4, 2 -> 4, 3 -> 4
      // 4 -> 8, 5 -> 8, 6 -> 8, 7 -> 8 ...
      size = size + tabWidth - size % tabWidth;
    } else {
      size++;
    }
  }

  return size;
}

module.exports = {
  getPrecedence,
  isExportDeclaration,
  getParentExportDeclaration,
  getPenultimate,
  getLast,
  getNextNonSpaceNonCommentCharacter,
  skipWhitespace,
  skipSpaces,
  skipNewline,
  isNextLineEmpty,
  isPreviousLineEmpty,
  hasNewline,
  hasNewlineInRange,
  hasSpaces,
  locStart,
  locEnd,
  setLocStart,
  setLocEnd,
  startsWithNoLookaheadToken,
  hasBlockComments,
  isBlockComment,
  getAlignmentSize
};