overleaf/services/web/public/js/ace/edit_session/fold_line.js

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define(function(require, exports, module) {
"use strict";

var Range = require("../range").Range;

/*
 * If an array is passed in, the folds are expected to be sorted already.
 */
function FoldLine(foldData, folds) {
    this.foldData = foldData;
    if (Array.isArray(folds)) {
        this.folds = folds;
    } else {
        folds = this.folds = [ folds ];
    }

    var last = folds[folds.length - 1]
    this.range = new Range(folds[0].start.row, folds[0].start.column,
                           last.end.row, last.end.column);
    this.start = this.range.start;
    this.end   = this.range.end;

    this.folds.forEach(function(fold) {
        fold.setFoldLine(this);
    }, this);
}

(function() {
    /*
     * Note: This doesn't update wrapData!
     */
    this.shiftRow = function(shift) {
        this.start.row += shift;
        this.end.row += shift;
        this.folds.forEach(function(fold) {
            fold.start.row += shift;
            fold.end.row += shift;
        });
    }

    this.addFold = function(fold) {
        if (fold.sameRow) {
            if (fold.start.row < this.startRow || fold.endRow > this.endRow) {
                throw new Error("Can't add a fold to this FoldLine as it has no connection");
            }
            this.folds.push(fold);
            this.folds.sort(function(a, b) {
                return -a.range.compareEnd(b.start.row, b.start.column);
            });
            if (this.range.compareEnd(fold.start.row, fold.start.column) > 0) {
                this.end.row = fold.end.row;
                this.end.column =  fold.end.column;
            } else if (this.range.compareStart(fold.end.row, fold.end.column) < 0) {
                this.start.row = fold.start.row;
                this.start.column = fold.start.column;
            }
        } else if (fold.start.row == this.end.row) {
            this.folds.push(fold);
            this.end.row = fold.end.row;
            this.end.column = fold.end.column;
        } else if (fold.end.row == this.start.row) {
            this.folds.unshift(fold);
            this.start.row = fold.start.row;
            this.start.column = fold.start.column;
        } else {
            throw new Error("Trying to add fold to FoldRow that doesn't have a matching row");
        }
        fold.foldLine = this;
    }

    this.containsRow = function(row) {
        return row >= this.start.row && row <= this.end.row;
    }

    this.walk = function(callback, endRow, endColumn) {
        var lastEnd = 0,
            folds = this.folds,
            fold,
            comp, stop, isNewRow = true;

        if (endRow == null) {
            endRow = this.end.row;
            endColumn = this.end.column;
        }

        for (var i = 0; i < folds.length; i++) {
            fold = folds[i];

            comp = fold.range.compareStart(endRow, endColumn);
            // This fold is after the endRow/Column.
            if (comp == -1) {
                callback(null, endRow, endColumn, lastEnd, isNewRow);
                return;
            }

            stop = callback(null, fold.start.row, fold.start.column, lastEnd, isNewRow);
            stop = !stop && callback(fold.placeholder, fold.start.row, fold.start.column, lastEnd);

            // If the user requested to stop the walk or endRow/endColumn is
            // inside of this fold (comp == 0), then end here.
            if (stop || comp == 0) {
                return;
            }

            // Note the new lastEnd might not be on the same line. However,
            // it's the callback's job to recognize this.
            isNewRow = !fold.sameRow;
            lastEnd = fold.end.column;
        }
        callback(null, endRow, endColumn, lastEnd, isNewRow);
    }

    this.getNextFoldTo = function(row, column) {
        var fold, cmp;
        for (var i = 0; i < this.folds.length; i++) {
            fold = this.folds[i];
            cmp = fold.range.compareEnd(row, column);
            if (cmp == -1) {
                return {
                    fold: fold,
                    kind: "after"
                };
            } else if (cmp == 0) {
                return {
                    fold: fold,
                    kind: "inside"
                }
            }
        }
        return null;
    }

    this.addRemoveChars = function(row, column, len) {
        var ret = this.getNextFoldTo(row, column),
            fold, folds;
        if (ret) {
            fold = ret.fold;
            if (ret.kind == "inside"
                && fold.start.column != column
                && fold.start.row != row)
            {
                //throwing here breaks whole editor
                //TODO: properly handle this
                window.console && window.console.log(row, column, fold);
            } else if (fold.start.row == row) {
                folds = this.folds;
                var i = folds.indexOf(fold);
                if (i == 0) {
                    this.start.column += len;
                }
                for (i; i < folds.length; i++) {
                    fold = folds[i];
                    fold.start.column += len;
                    if (!fold.sameRow) {
                        return;
                    }
                    fold.end.column += len;
                }
                this.end.column += len;
            }
        }
    }

    this.split = function(row, column) {
        var fold = this.getNextFoldTo(row, column).fold;
        var folds = this.folds;
        var foldData = this.foldData;

        if (!fold)
            return null;

        var i = folds.indexOf(fold);
        var foldBefore = folds[i - 1];
        this.end.row = foldBefore.end.row;
        this.end.column = foldBefore.end.column;

        // Remove the folds after row/column and create a new FoldLine
        // containing these removed folds.
        folds = folds.splice(i, folds.length - i);

        var newFoldLine = new FoldLine(foldData, folds);
        foldData.splice(foldData.indexOf(this) + 1, 0, newFoldLine);
        return newFoldLine;
    }

    this.merge = function(foldLineNext) {
        var folds = foldLineNext.folds;
        for (var i = 0; i < folds.length; i++) {
            this.addFold(folds[i]);
        }
        // Remove the foldLineNext - no longer needed, as
        // it's merged now with foldLineNext.
        var foldData = this.foldData;
        foldData.splice(foldData.indexOf(foldLineNext), 1);
    }

    this.toString = function() {
        var ret = [this.range.toString() + ": [" ];

        this.folds.forEach(function(fold) {
            ret.push("  " + fold.toString());
        });
        ret.push("]")
        return ret.join("\n");
    }

    this.idxToPosition = function(idx) {
        var lastFoldEndColumn = 0;
        var fold;

        for (var i = 0; i < this.folds.length; i++) {
            var fold = this.folds[i];

            idx -= fold.start.column - lastFoldEndColumn;
            if (idx < 0) {
                return {
                    row: fold.start.row,
                    column: fold.start.column + idx
                };
            }

            idx -= fold.placeholder.length;
            if (idx < 0) {
                return fold.start;
            }

            lastFoldEndColumn = fold.end.column;
        }

        return {
            row: this.end.row,
            column: this.end.column + idx
        };
    }
}).call(FoldLine.prototype);

exports.FoldLine = FoldLine;
});