initial commit

node_modules/recast/lib/lines.js

@@ -0,0 +1,895 @@
+var assert = require("assert");
+var sourceMap = require("source-map");
+var normalizeOptions = require("./options").normalize;
+var secretKey = require("private").makeUniqueKey();
+var types = require("./types");
+var isString = types.builtInTypes.string;
+var comparePos = require("./util").comparePos;
+var Mapping = require("./mapping");
+
+// Goals:
+// 1. Minimize new string creation.
+// 2. Keep (de)identation O(lines) time.
+// 3. Permit negative indentations.
+// 4. Enforce immutability.
+// 5. No newline characters.
+
+function getSecret(lines) {
+    return lines[secretKey];
+}
+
+function Lines(infos, sourceFileName) {
+    assert.ok(this instanceof Lines);
+    assert.ok(infos.length > 0);
+
+    if (sourceFileName) {
+        isString.assert(sourceFileName);
+    } else {
+        sourceFileName = null;
+    }
+
+    Object.defineProperty(this, secretKey, {
+        value: {
+            infos: infos,
+            mappings: [],
+            name: sourceFileName,
+            cachedSourceMap: null
+        }
+    });
+
+    if (sourceFileName) {
+        getSecret(this).mappings.push(new Mapping(this, {
+            start: this.firstPos(),
+            end: this.lastPos()
+        }));
+    }
+}
+
+// Exposed for instanceof checks. The fromString function should be used
+// to create new Lines objects.
+exports.Lines = Lines;
+var Lp = Lines.prototype;
+
+// These properties used to be assigned to each new object in the Lines
+// constructor, but we can more efficiently stuff them into the secret and
+// let these lazy accessors compute their values on-the-fly.
+Object.defineProperties(Lp, {
+    length: {
+        get: function() {
+            return getSecret(this).infos.length;
+        }
+    },
+
+    name: {
+        get: function() {
+            return getSecret(this).name;
+        }
+    }
+});
+
+function copyLineInfo(info) {
+    return {
+        line: info.line,
+        indent: info.indent,
+        locked: info.locked,
+        sliceStart: info.sliceStart,
+        sliceEnd: info.sliceEnd
+    };
+}
+
+var fromStringCache = {};
+var hasOwn = fromStringCache.hasOwnProperty;
+var maxCacheKeyLen = 10;
+
+function countSpaces(spaces, tabWidth) {
+    var count = 0;
+    var len = spaces.length;
+
+    for (var i = 0; i < len; ++i) {
+        switch (spaces.charCodeAt(i)) {
+        case 9: // '\t'
+            assert.strictEqual(typeof tabWidth, "number");
+            assert.ok(tabWidth > 0);
+
+            var next = Math.ceil(count / tabWidth) * tabWidth;
+            if (next === count) {
+                count += tabWidth;
+            } else {
+                count = next;
+            }
+
+            break;
+
+        case 11: // '\v'
+        case 12: // '\f'
+        case 13: // '\r'
+        case 0xfeff: // zero-width non-breaking space
+            // These characters contribute nothing to indentation.
+            break;
+
+        case 32: // ' '
+        default: // Treat all other whitespace like ' '.
+            count += 1;
+            break;
+        }
+    }
+
+    return count;
+}
+exports.countSpaces = countSpaces;
+
+var leadingSpaceExp = /^\s*/;
+
+// As specified here: http://www.ecma-international.org/ecma-262/6.0/#sec-line-terminators
+var lineTerminatorSeqExp =
+    /\u000D\u000A|\u000D(?!\u000A)|\u000A|\u2028|\u2029/;
+
+/**
+ * @param {Object} options - Options object that configures printing.
+ */
+function fromString(string, options) {
+    if (string instanceof Lines)
+        return string;
+
+    string += "";
+
+    var tabWidth = options && options.tabWidth;
+    var tabless = string.indexOf("\t") < 0;
+    var locked = !! (options && options.locked);
+    var cacheable = !options && tabless && (string.length <= maxCacheKeyLen);
+
+    assert.ok(tabWidth || tabless, "No tab width specified but encountered tabs in string\n" + string);
+
+    if (cacheable && hasOwn.call(fromStringCache, string))
+        return fromStringCache[string];
+
+    var lines = new Lines(string.split(lineTerminatorSeqExp).map(function(line) {
+        var spaces = leadingSpaceExp.exec(line)[0];
+        return {
+            line: line,
+            indent: countSpaces(spaces, tabWidth),
+            // Boolean indicating whether this line can be reindented.
+            locked: locked,
+            sliceStart: spaces.length,
+            sliceEnd: line.length
+        };
+    }), normalizeOptions(options).sourceFileName);
+
+    if (cacheable)
+        fromStringCache[string] = lines;
+
+    return lines;
+}
+exports.fromString = fromString;
+
+function isOnlyWhitespace(string) {
+    return !/\S/.test(string);
+}
+
+Lp.toString = function(options) {
+    return this.sliceString(this.firstPos(), this.lastPos(), options);
+};
+
+Lp.getSourceMap = function(sourceMapName, sourceRoot) {
+    if (!sourceMapName) {
+        // Although we could make up a name or generate an anonymous
+        // source map, instead we assume that any consumer who does not
+        // provide a name does not actually want a source map.
+        return null;
+    }
+
+    var targetLines = this;
+
+    function updateJSON(json) {
+        json = json || {};
+
+        isString.assert(sourceMapName);
+        json.file = sourceMapName;
+
+        if (sourceRoot) {
+            isString.assert(sourceRoot);
+            json.sourceRoot = sourceRoot;
+        }
+
+        return json;
+    }
+
+    var secret = getSecret(targetLines);
+    if (secret.cachedSourceMap) {
+        // Since Lines objects are immutable, we can reuse any source map
+        // that was previously generated. Nevertheless, we return a new
+        // JSON object here to protect the cached source map from outside
+        // modification.
+        return updateJSON(secret.cachedSourceMap.toJSON());
+    }
+
+    var smg = new sourceMap.SourceMapGenerator(updateJSON());
+    var sourcesToContents = {};
+
+    secret.mappings.forEach(function(mapping) {
+        var sourceCursor = mapping.sourceLines.skipSpaces(
+            mapping.sourceLoc.start
+        ) || mapping.sourceLines.lastPos();
+
+        var targetCursor = targetLines.skipSpaces(
+            mapping.targetLoc.start
+        ) || targetLines.lastPos();
+
+        while (comparePos(sourceCursor, mapping.sourceLoc.end) < 0 &&
+               comparePos(targetCursor, mapping.targetLoc.end) < 0) {
+
+            var sourceChar = mapping.sourceLines.charAt(sourceCursor);
+            var targetChar = targetLines.charAt(targetCursor);
+            assert.strictEqual(sourceChar, targetChar);
+
+            var sourceName = mapping.sourceLines.name;
+
+            // Add mappings one character at a time for maximum resolution.
+            smg.addMapping({
+                source: sourceName,
+                original: { line: sourceCursor.line,
+                            column: sourceCursor.column },
+                generated: { line: targetCursor.line,
+                             column: targetCursor.column }
+            });
+
+            if (!hasOwn.call(sourcesToContents, sourceName)) {
+                var sourceContent = mapping.sourceLines.toString();
+                smg.setSourceContent(sourceName, sourceContent);
+                sourcesToContents[sourceName] = sourceContent;
+            }
+
+            targetLines.nextPos(targetCursor, true);
+            mapping.sourceLines.nextPos(sourceCursor, true);
+        }
+    });
+
+    secret.cachedSourceMap = smg;
+
+    return smg.toJSON();
+};
+
+Lp.bootstrapCharAt = function(pos) {
+    assert.strictEqual(typeof pos, "object");
+    assert.strictEqual(typeof pos.line, "number");
+    assert.strictEqual(typeof pos.column, "number");
+
+    var line = pos.line,
+        column = pos.column,
+        strings = this.toString().split(lineTerminatorSeqExp),
+        string = strings[line - 1];
+
+    if (typeof string === "undefined")
+        return "";
+
+    if (column === string.length &&
+        line < strings.length)
+        return "\n";
+
+    if (column >= string.length)
+        return "";
+
+    return string.charAt(column);
+};
+
+Lp.charAt = function(pos) {
+    assert.strictEqual(typeof pos, "object");
+    assert.strictEqual(typeof pos.line, "number");
+    assert.strictEqual(typeof pos.column, "number");
+
+    var line = pos.line,
+        column = pos.column,
+        secret = getSecret(this),
+        infos = secret.infos,
+        info = infos[line - 1],
+        c = column;
+
+    if (typeof info === "undefined" || c < 0)
+        return "";
+
+    var indent = this.getIndentAt(line);
+    if (c < indent)
+        return " ";
+
+    c += info.sliceStart - indent;
+
+    if (c === info.sliceEnd &&
+        line < this.length)
+        return "\n";
+
+    if (c >= info.sliceEnd)
+        return "";
+
+    return info.line.charAt(c);
+};
+
+Lp.stripMargin = function(width, skipFirstLine) {
+    if (width === 0)
+        return this;
+
+    assert.ok(width > 0, "negative margin: " + width);
+
+    if (skipFirstLine && this.length === 1)
+        return this;
+
+    var secret = getSecret(this);
+
+    var lines = new Lines(secret.infos.map(function(info, i) {
+        if (info.line && (i > 0 || !skipFirstLine)) {
+            info = copyLineInfo(info);
+            info.indent = Math.max(0, info.indent - width);
+        }
+        return info;
+    }));
+
+    if (secret.mappings.length > 0) {
+        var newMappings = getSecret(lines).mappings;
+        assert.strictEqual(newMappings.length, 0);
+        secret.mappings.forEach(function(mapping) {
+            newMappings.push(mapping.indent(width, skipFirstLine, true));
+        });
+    }
+
+    return lines;
+};
+
+Lp.indent = function(by) {
+    if (by === 0)
+        return this;
+
+    var secret = getSecret(this);
+
+    var lines = new Lines(secret.infos.map(function(info) {
+        if (info.line && ! info.locked) {
+            info = copyLineInfo(info);
+            info.indent += by;
+        }
+        return info
+    }));
+
+    if (secret.mappings.length > 0) {
+        var newMappings = getSecret(lines).mappings;
+        assert.strictEqual(newMappings.length, 0);
+        secret.mappings.forEach(function(mapping) {
+            newMappings.push(mapping.indent(by));
+        });
+    }
+
+    return lines;
+};
+
+Lp.indentTail = function(by) {
+    if (by === 0)
+        return this;
+
+    if (this.length < 2)
+        return this;
+
+    var secret = getSecret(this);
+
+    var lines = new Lines(secret.infos.map(function(info, i) {
+        if (i > 0 && info.line && ! info.locked) {
+            info = copyLineInfo(info);
+            info.indent += by;
+        }
+
+        return info;
+    }));
+
+    if (secret.mappings.length > 0) {
+        var newMappings = getSecret(lines).mappings;
+        assert.strictEqual(newMappings.length, 0);
+        secret.mappings.forEach(function(mapping) {
+            newMappings.push(mapping.indent(by, true));
+        });
+    }
+
+    return lines;
+};
+
+Lp.lockIndentTail = function () {
+    if (this.length < 2) {
+        return this;
+    }
+
+    var infos = getSecret(this).infos;
+
+    return new Lines(infos.map(function (info, i) {
+        info = copyLineInfo(info);
+        info.locked = i > 0;
+        return info;
+    }));
+};
+
+Lp.getIndentAt = function(line) {
+    assert.ok(line >= 1, "no line " + line + " (line numbers start from 1)");
+    var secret = getSecret(this),
+        info = secret.infos[line - 1];
+    return Math.max(info.indent, 0);
+};
+
+Lp.guessTabWidth = function() {
+    var secret = getSecret(this);
+    if (hasOwn.call(secret, "cachedTabWidth")) {
+        return secret.cachedTabWidth;
+    }
+
+    var counts = []; // Sparse array.
+    var lastIndent = 0;
+
+    for (var line = 1, last = this.length; line <= last; ++line) {
+        var info = secret.infos[line - 1];
+        var sliced = info.line.slice(info.sliceStart, info.sliceEnd);
+
+        // Whitespace-only lines don't tell us much about the likely tab
+        // width of this code.
+        if (isOnlyWhitespace(sliced)) {
+            continue;
+        }
+
+        var diff = Math.abs(info.indent - lastIndent);
+        counts[diff] = ~~counts[diff] + 1;
+        lastIndent = info.indent;
+    }
+
+    var maxCount = -1;
+    var result = 2;
+
+    for (var tabWidth = 1;
+         tabWidth < counts.length;
+         tabWidth += 1) {
+        if (hasOwn.call(counts, tabWidth) &&
+            counts[tabWidth] > maxCount) {
+            maxCount = counts[tabWidth];
+            result = tabWidth;
+        }
+    }
+
+    return secret.cachedTabWidth = result;
+};
+
+// Determine if the list of lines has a first line that starts with a //
+// or /* comment. If this is the case, the code may need to be wrapped in
+// parens to avoid ASI issues.
+Lp.startsWithComment = function () {
+    var secret = getSecret(this);
+    if (secret.infos.length === 0) {
+        return false;
+    }
+    var firstLineInfo = secret.infos[0],
+        sliceStart = firstLineInfo.sliceStart,
+        sliceEnd = firstLineInfo.sliceEnd,
+        firstLine = firstLineInfo.line.slice(sliceStart, sliceEnd).trim();
+    return firstLine.length === 0 ||
+        firstLine.slice(0, 2) === "//" ||
+        firstLine.slice(0, 2) === "/*";
+};
+
+Lp.isOnlyWhitespace = function() {
+    return isOnlyWhitespace(this.toString());
+};
+
+Lp.isPrecededOnlyByWhitespace = function(pos) {
+    var secret = getSecret(this);
+    var info = secret.infos[pos.line - 1];
+    var indent = Math.max(info.indent, 0);
+
+    var diff = pos.column - indent;
+    if (diff <= 0) {
+        // If pos.column does not exceed the indentation amount, then
+        // there must be only whitespace before it.
+        return true;
+    }
+
+    var start = info.sliceStart;
+    var end = Math.min(start + diff, info.sliceEnd);
+    var prefix = info.line.slice(start, end);
+
+    return isOnlyWhitespace(prefix);
+};
+
+Lp.getLineLength = function(line) {
+    var secret = getSecret(this),
+        info = secret.infos[line - 1];
+    return this.getIndentAt(line) + info.sliceEnd - info.sliceStart;
+};
+
+Lp.nextPos = function(pos, skipSpaces) {
+    var l = Math.max(pos.line, 0),
+        c = Math.max(pos.column, 0);
+
+    if (c < this.getLineLength(l)) {
+        pos.column += 1;
+
+        return skipSpaces
+            ? !!this.skipSpaces(pos, false, true)
+            : true;
+    }
+
+    if (l < this.length) {
+        pos.line += 1;
+        pos.column = 0;
+
+        return skipSpaces
+            ? !!this.skipSpaces(pos, false, true)
+            : true;
+    }
+
+    return false;
+};
+
+Lp.prevPos = function(pos, skipSpaces) {
+    var l = pos.line,
+        c = pos.column;
+
+    if (c < 1) {
+        l -= 1;
+
+        if (l < 1)
+            return false;
+
+        c = this.getLineLength(l);
+
+    } else {
+        c = Math.min(c - 1, this.getLineLength(l));
+    }
+
+    pos.line = l;
+    pos.column = c;
+
+    return skipSpaces
+        ? !!this.skipSpaces(pos, true, true)
+        : true;
+};
+
+Lp.firstPos = function() {
+    // Trivial, but provided for completeness.
+    return { line: 1, column: 0 };
+};
+
+Lp.lastPos = function() {
+    return {
+        line: this.length,
+        column: this.getLineLength(this.length)
+    };
+};
+
+Lp.skipSpaces = function(pos, backward, modifyInPlace) {
+    if (pos) {
+        pos = modifyInPlace ? pos : {
+            line: pos.line,
+            column: pos.column
+        };
+    } else if (backward) {
+        pos = this.lastPos();
+    } else {
+        pos = this.firstPos();
+    }
+
+    if (backward) {
+        while (this.prevPos(pos)) {
+            if (!isOnlyWhitespace(this.charAt(pos)) &&
+                this.nextPos(pos)) {
+                return pos;
+            }
+        }
+
+        return null;
+
+    } else {
+        while (isOnlyWhitespace(this.charAt(pos))) {
+            if (!this.nextPos(pos)) {
+                return null;
+            }
+        }
+
+        return pos;
+    }
+};
+
+Lp.trimLeft = function() {
+    var pos = this.skipSpaces(this.firstPos(), false, true);
+    return pos ? this.slice(pos) : emptyLines;
+};
+
+Lp.trimRight = function() {
+    var pos = this.skipSpaces(this.lastPos(), true, true);
+    return pos ? this.slice(this.firstPos(), pos) : emptyLines;
+};
+
+Lp.trim = function() {
+    var start = this.skipSpaces(this.firstPos(), false, true);
+    if (start === null)
+        return emptyLines;
+
+    var end = this.skipSpaces(this.lastPos(), true, true);
+    assert.notStrictEqual(end, null);
+
+    return this.slice(start, end);
+};
+
+Lp.eachPos = function(callback, startPos, skipSpaces) {
+    var pos = this.firstPos();
+
+    if (startPos) {
+        pos.line = startPos.line,
+        pos.column = startPos.column
+    }
+
+    if (skipSpaces && !this.skipSpaces(pos, false, true)) {
+        return; // Encountered nothing but spaces.
+    }
+
+    do callback.call(this, pos);
+    while (this.nextPos(pos, skipSpaces));
+};
+
+Lp.bootstrapSlice = function(start, end) {
+    var strings = this.toString().split(
+        lineTerminatorSeqExp
+    ).slice(
+        start.line - 1,
+        end.line
+    );
+
+    strings.push(strings.pop().slice(0, end.column));
+    strings[0] = strings[0].slice(start.column);
+
+    return fromString(strings.join("\n"));
+};
+
+Lp.slice = function(start, end) {
+    if (!end) {
+        if (!start) {
+            // The client seems to want a copy of this Lines object, but
+            // Lines objects are immutable, so it's perfectly adequate to
+            // return the same object.
+            return this;
+        }
+
+        // Slice to the end if no end position was provided.
+        end = this.lastPos();
+    }
+
+    var secret = getSecret(this);
+    var sliced = secret.infos.slice(start.line - 1, end.line);
+
+    if (start.line === end.line) {
+        sliced[0] = sliceInfo(sliced[0], start.column, end.column);
+    } else {
+        assert.ok(start.line < end.line);
+        sliced[0] = sliceInfo(sliced[0], start.column);
+        sliced.push(sliceInfo(sliced.pop(), 0, end.column));
+    }
+
+    var lines = new Lines(sliced);
+
+    if (secret.mappings.length > 0) {
+        var newMappings = getSecret(lines).mappings;
+        assert.strictEqual(newMappings.length, 0);
+        secret.mappings.forEach(function(mapping) {
+            var sliced = mapping.slice(this, start, end);
+            if (sliced) {
+                newMappings.push(sliced);
+            }
+        }, this);
+    }
+
+    return lines;
+};
+
+function sliceInfo(info, startCol, endCol) {
+    var sliceStart = info.sliceStart;
+    var sliceEnd = info.sliceEnd;
+    var indent = Math.max(info.indent, 0);
+    var lineLength = indent + sliceEnd - sliceStart;
+
+    if (typeof endCol === "undefined") {
+        endCol = lineLength;
+    }
+
+    startCol = Math.max(startCol, 0);
+    endCol = Math.min(endCol, lineLength);
+    endCol = Math.max(endCol, startCol);
+
+    if (endCol < indent) {
+        indent = endCol;
+        sliceEnd = sliceStart;
+    } else {
+        sliceEnd -= lineLength - endCol;
+    }
+
+    lineLength = endCol;
+    lineLength -= startCol;
+
+    if (startCol < indent) {
+        indent -= startCol;
+    } else {
+        startCol -= indent;
+        indent = 0;
+        sliceStart += startCol;
+    }
+
+    assert.ok(indent >= 0);
+    assert.ok(sliceStart <= sliceEnd);
+    assert.strictEqual(lineLength, indent + sliceEnd - sliceStart);
+
+    if (info.indent === indent &&
+        info.sliceStart === sliceStart &&
+        info.sliceEnd === sliceEnd) {
+        return info;
+    }
+
+    return {
+        line: info.line,
+        indent: indent,
+        // A destructive slice always unlocks indentation.
+        locked: false,
+        sliceStart: sliceStart,
+        sliceEnd: sliceEnd
+    };
+}
+
+Lp.bootstrapSliceString = function(start, end, options) {
+    return this.slice(start, end).toString(options);
+};
+
+Lp.sliceString = function(start, end, options) {
+    if (!end) {
+        if (!start) {
+            // The client seems to want a copy of this Lines object, but
+            // Lines objects are immutable, so it's perfectly adequate to
+            // return the same object.
+            return this;
+        }
+
+        // Slice to the end if no end position was provided.
+        end = this.lastPos();
+    }
+
+    options = normalizeOptions(options);
+
+    var infos = getSecret(this).infos;
+    var parts = [];
+    var tabWidth = options.tabWidth;
+
+    for (var line = start.line; line <= end.line; ++line) {
+        var info = infos[line - 1];
+
+        if (line === start.line) {
+            if (line === end.line) {
+                info = sliceInfo(info, start.column, end.column);
+            } else {
+                info = sliceInfo(info, start.column);
+            }
+        } else if (line === end.line) {
+            info = sliceInfo(info, 0, end.column);
+        }
+
+        var indent = Math.max(info.indent, 0);
+
+        var before = info.line.slice(0, info.sliceStart);
+        if (options.reuseWhitespace &&
+            isOnlyWhitespace(before) &&
+            countSpaces(before, options.tabWidth) === indent) {
+            // Reuse original spaces if the indentation is correct.
+            parts.push(info.line.slice(0, info.sliceEnd));
+            continue;
+        }
+
+        var tabs = 0;
+        var spaces = indent;
+
+        if (options.useTabs) {
+            tabs = Math.floor(indent / tabWidth);
+            spaces -= tabs * tabWidth;
+        }
+
+        var result = "";
+
+        if (tabs > 0) {
+            result += new Array(tabs + 1).join("\t");
+        }
+
+        if (spaces > 0) {
+            result += new Array(spaces + 1).join(" ");
+        }
+
+        result += info.line.slice(info.sliceStart, info.sliceEnd);
+
+        parts.push(result);
+    }
+
+    return parts.join(options.lineTerminator);
+};
+
+Lp.isEmpty = function() {
+    return this.length < 2 && this.getLineLength(1) < 1;
+};
+
+Lp.join = function(elements) {
+    var separator = this;
+    var separatorSecret = getSecret(separator);
+    var infos = [];
+    var mappings = [];
+    var prevInfo;
+
+    function appendSecret(secret) {
+        if (secret === null)
+            return;
+
+        if (prevInfo) {
+            var info = secret.infos[0];
+            var indent = new Array(info.indent + 1).join(" ");
+            var prevLine = infos.length;
+            var prevColumn = Math.max(prevInfo.indent, 0) +
+                prevInfo.sliceEnd - prevInfo.sliceStart;
+
+            prevInfo.line = prevInfo.line.slice(
+                0, prevInfo.sliceEnd) + indent + info.line.slice(
+                    info.sliceStart, info.sliceEnd);
+
+            // If any part of a line is indentation-locked, the whole line
+            // will be indentation-locked.
+            prevInfo.locked = prevInfo.locked || info.locked;
+
+            prevInfo.sliceEnd = prevInfo.line.length;
+
+            if (secret.mappings.length > 0) {
+                secret.mappings.forEach(function(mapping) {
+                    mappings.push(mapping.add(prevLine, prevColumn));
+                });
+            }
+
+        } else if (secret.mappings.length > 0) {
+            mappings.push.apply(mappings, secret.mappings);
+        }
+
+        secret.infos.forEach(function(info, i) {
+            if (!prevInfo || i > 0) {
+                prevInfo = copyLineInfo(info);
+                infos.push(prevInfo);
+            }
+        });
+    }
+
+    function appendWithSeparator(secret, i) {
+        if (i > 0)
+            appendSecret(separatorSecret);
+        appendSecret(secret);
+    }
+
+    elements.map(function(elem) {
+        var lines = fromString(elem);
+        if (lines.isEmpty())
+            return null;
+        return getSecret(lines);
+    }).forEach(separator.isEmpty()
+               ? appendSecret
+               : appendWithSeparator);
+
+    if (infos.length < 1)
+        return emptyLines;
+
+    var lines = new Lines(infos);
+
+    getSecret(lines).mappings = mappings;
+
+    return lines;
+};
+
+exports.concat = function(elements) {
+    return emptyLines.join(elements);
+};
+
+Lp.concat = function(other) {
+    var args = arguments,
+        list = [this];
+    list.push.apply(list, args);
+    assert.strictEqual(list.length, args.length + 1);
+    return emptyLines.join(list);
+};
+
+// The emptyLines object needs to be created all the way down here so that
+// Lines.prototype will be fully populated.
+var emptyLines = fromString("");