X-Git-Url: https://git.josue.xyz/?p=VSoRC%2F.git;a=blobdiff_plain;f=node_modules%2Fxterm%2Fsrc%2Fcommon%2Fbuffer%2FBuffer.ts;fp=node_modules%2Fxterm%2Fsrc%2Fcommon%2Fbuffer%2FBuffer.ts;h=152bab7a3c1bb3caff791d3c16895d0b188155ba;hp=0000000000000000000000000000000000000000;hb=4339da12467b75fb8b6ca831f4bf0081c485ed2c;hpb=af450fde25a9ccf4767b29254c463ffb8ef25237

diff --git a/node_modules/xterm/src/common/buffer/Buffer.ts b/node_modules/xterm/src/common/buffer/Buffer.ts
new file mode 100644
index 0000000..152bab7
--- /dev/null
+++ b/node_modules/xterm/src/common/buffer/Buffer.ts
@@ -0,0 +1,671 @@
+/**
+ * Copyright (c) 2017 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { CircularList, IInsertEvent } from 'common/CircularList';
+import { IBuffer, BufferIndex, IBufferStringIterator, IBufferStringIteratorResult } from 'common/buffer/Types';
+import { IBufferLine, ICellData, IAttributeData, ICharset } from 'common/Types';
+import { BufferLine, DEFAULT_ATTR_DATA } from 'common/buffer/BufferLine';
+import { CellData } from 'common/buffer/CellData';
+import { NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, WHITESPACE_CELL_CHAR, WHITESPACE_CELL_WIDTH, WHITESPACE_CELL_CODE, CHAR_DATA_WIDTH_INDEX, CHAR_DATA_CHAR_INDEX } from 'common/buffer/Constants';
+import { reflowLargerApplyNewLayout, reflowLargerCreateNewLayout, reflowLargerGetLinesToRemove, reflowSmallerGetNewLineLengths, getWrappedLineTrimmedLength } from 'common/buffer/BufferReflow';
+import { Marker } from 'common/buffer/Marker';
+import { IOptionsService, IBufferService } from 'common/services/Services';
+import { DEFAULT_CHARSET } from 'common/data/Charsets';
+
+export const MAX_BUFFER_SIZE = 4294967295; // 2^32 - 1
+
+/**
+ * This class represents a terminal buffer (an internal state of the terminal), where the
+ * following information is stored (in high-level):
+ *   - text content of this particular buffer
+ *   - cursor position
+ *   - scroll position
+ */
+export class Buffer implements IBuffer {
+  public lines: CircularList<IBufferLine>;
+  public ydisp: number = 0;
+  public ybase: number = 0;
+  public y: number = 0;
+  public x: number = 0;
+  public scrollBottom: number;
+  public scrollTop: number;
+  // TODO: Type me
+  public tabs: any;
+  public savedY: number = 0;
+  public savedX: number = 0;
+  public savedCurAttrData = DEFAULT_ATTR_DATA.clone();
+  public savedCharset: ICharset | null = DEFAULT_CHARSET;
+  public markers: Marker[] = [];
+  private _nullCell: ICellData = CellData.fromCharData([0, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]);
+  private _whitespaceCell: ICellData = CellData.fromCharData([0, WHITESPACE_CELL_CHAR, WHITESPACE_CELL_WIDTH, WHITESPACE_CELL_CODE]);
+  private _cols: number;
+  private _rows: number;
+
+  constructor(
+    private _hasScrollback: boolean,
+    private _optionsService: IOptionsService,
+    private _bufferService: IBufferService
+  ) {
+    this._cols = this._bufferService.cols;
+    this._rows = this._bufferService.rows;
+    this.lines = new CircularList<IBufferLine>(this._getCorrectBufferLength(this._rows));
+    this.scrollTop = 0;
+    this.scrollBottom = this._rows - 1;
+    this.setupTabStops();
+  }
+
+  public getNullCell(attr?: IAttributeData): ICellData {
+    if (attr) {
+      this._nullCell.fg = attr.fg;
+      this._nullCell.bg = attr.bg;
+    } else {
+      this._nullCell.fg = 0;
+      this._nullCell.bg = 0;
+    }
+    return this._nullCell;
+  }
+
+  public getWhitespaceCell(attr?: IAttributeData): ICellData {
+    if (attr) {
+      this._whitespaceCell.fg = attr.fg;
+      this._whitespaceCell.bg = attr.bg;
+    } else {
+      this._whitespaceCell.fg = 0;
+      this._whitespaceCell.bg = 0;
+    }
+    return this._whitespaceCell;
+  }
+
+  public getBlankLine(attr: IAttributeData, isWrapped?: boolean): IBufferLine {
+    return new BufferLine(this._bufferService.cols, this.getNullCell(attr), isWrapped);
+  }
+
+  public get hasScrollback(): boolean {
+    return this._hasScrollback && this.lines.maxLength > this._rows;
+  }
+
+  public get isCursorInViewport(): boolean {
+    const absoluteY = this.ybase + this.y;
+    const relativeY = absoluteY - this.ydisp;
+    return (relativeY >= 0 && relativeY < this._rows);
+  }
+
+  /**
+   * Gets the correct buffer length based on the rows provided, the terminal's
+   * scrollback and whether this buffer is flagged to have scrollback or not.
+   * @param rows The terminal rows to use in the calculation.
+   */
+  private _getCorrectBufferLength(rows: number): number {
+    if (!this._hasScrollback) {
+      return rows;
+    }
+
+    const correctBufferLength = rows + this._optionsService.options.scrollback;
+
+    return correctBufferLength > MAX_BUFFER_SIZE ? MAX_BUFFER_SIZE : correctBufferLength;
+  }
+
+  /**
+   * Fills the buffer's viewport with blank lines.
+   */
+  public fillViewportRows(fillAttr?: IAttributeData): void {
+    if (this.lines.length === 0) {
+      if (fillAttr === undefined) {
+        fillAttr = DEFAULT_ATTR_DATA;
+      }
+      let i = this._rows;
+      while (i--) {
+        this.lines.push(this.getBlankLine(fillAttr));
+      }
+    }
+  }
+
+  /**
+   * Clears the buffer to it's initial state, discarding all previous data.
+   */
+  public clear(): void {
+    this.ydisp = 0;
+    this.ybase = 0;
+    this.y = 0;
+    this.x = 0;
+    this.lines = new CircularList<IBufferLine>(this._getCorrectBufferLength(this._rows));
+    this.scrollTop = 0;
+    this.scrollBottom = this._rows - 1;
+    this.setupTabStops();
+  }
+
+  /**
+   * Resizes the buffer, adjusting its data accordingly.
+   * @param newCols The new number of columns.
+   * @param newRows The new number of rows.
+   */
+  public resize(newCols: number, newRows: number): void {
+    // store reference to null cell with default attrs
+    const nullCell = this.getNullCell(DEFAULT_ATTR_DATA);
+
+    // Increase max length if needed before adjustments to allow space to fill
+    // as required.
+    const newMaxLength = this._getCorrectBufferLength(newRows);
+    if (newMaxLength > this.lines.maxLength) {
+      this.lines.maxLength = newMaxLength;
+    }
+
+    // The following adjustments should only happen if the buffer has been
+    // initialized/filled.
+    if (this.lines.length > 0) {
+      // Deal with columns increasing (reducing needs to happen after reflow)
+      if (this._cols < newCols) {
+        for (let i = 0; i < this.lines.length; i++) {
+          this.lines.get(i)!.resize(newCols, nullCell);
+        }
+      }
+
+      // Resize rows in both directions as needed
+      let addToY = 0;
+      if (this._rows < newRows) {
+        for (let y = this._rows; y < newRows; y++) {
+          if (this.lines.length < newRows + this.ybase) {
+            if (this._optionsService.options.windowsMode) {
+              // Just add the new missing rows on Windows as conpty reprints the screen with it's
+              // view of the world. Once a line enters scrollback for conpty it remains there
+              this.lines.push(new BufferLine(newCols, nullCell));
+            } else {
+              if (this.ybase > 0 && this.lines.length <= this.ybase + this.y + addToY + 1) {
+                // There is room above the buffer and there are no empty elements below the line,
+                // scroll up
+                this.ybase--;
+                addToY++;
+                if (this.ydisp > 0) {
+                  // Viewport is at the top of the buffer, must increase downwards
+                  this.ydisp--;
+                }
+              } else {
+                // Add a blank line if there is no buffer left at the top to scroll to, or if there
+                // are blank lines after the cursor
+                this.lines.push(new BufferLine(newCols, nullCell));
+              }
+            }
+          }
+        }
+      } else { // (this._rows >= newRows)
+        for (let y = this._rows; y > newRows; y--) {
+          if (this.lines.length > newRows + this.ybase) {
+            if (this.lines.length > this.ybase + this.y + 1) {
+              // The line is a blank line below the cursor, remove it
+              this.lines.pop();
+            } else {
+              // The line is the cursor, scroll down
+              this.ybase++;
+              this.ydisp++;
+            }
+          }
+        }
+      }
+
+      // Reduce max length if needed after adjustments, this is done after as it
+      // would otherwise cut data from the bottom of the buffer.
+      if (newMaxLength < this.lines.maxLength) {
+        // Trim from the top of the buffer and adjust ybase and ydisp.
+        const amountToTrim = this.lines.length - newMaxLength;
+        if (amountToTrim > 0) {
+          this.lines.trimStart(amountToTrim);
+          this.ybase = Math.max(this.ybase - amountToTrim, 0);
+          this.ydisp = Math.max(this.ydisp - amountToTrim, 0);
+          this.savedY = Math.max(this.savedY - amountToTrim, 0);
+        }
+        this.lines.maxLength = newMaxLength;
+      }
+
+      // Make sure that the cursor stays on screen
+      this.x = Math.min(this.x, newCols - 1);
+      this.y = Math.min(this.y, newRows - 1);
+      if (addToY) {
+        this.y += addToY;
+      }
+      this.savedX = Math.min(this.savedX, newCols - 1);
+
+      this.scrollTop = 0;
+    }
+
+    this.scrollBottom = newRows - 1;
+
+    if (this._isReflowEnabled) {
+      this._reflow(newCols, newRows);
+
+      // Trim the end of the line off if cols shrunk
+      if (this._cols > newCols) {
+        for (let i = 0; i < this.lines.length; i++) {
+          this.lines.get(i)!.resize(newCols, nullCell);
+        }
+      }
+    }
+
+    this._cols = newCols;
+    this._rows = newRows;
+  }
+
+  private get _isReflowEnabled(): boolean {
+    return this._hasScrollback && !this._optionsService.options.windowsMode;
+  }
+
+  private _reflow(newCols: number, newRows: number): void {
+    if (this._cols === newCols) {
+      return;
+    }
+
+    // Iterate through rows, ignore the last one as it cannot be wrapped
+    if (newCols > this._cols) {
+      this._reflowLarger(newCols, newRows);
+    } else {
+      this._reflowSmaller(newCols, newRows);
+    }
+  }
+
+  private _reflowLarger(newCols: number, newRows: number): void {
+    const toRemove: number[] = reflowLargerGetLinesToRemove(this.lines, this._cols, newCols, this.ybase + this.y, this.getNullCell(DEFAULT_ATTR_DATA));
+    if (toRemove.length > 0) {
+      const newLayoutResult = reflowLargerCreateNewLayout(this.lines, toRemove);
+      reflowLargerApplyNewLayout(this.lines, newLayoutResult.layout);
+      this._reflowLargerAdjustViewport(newCols, newRows, newLayoutResult.countRemoved);
+    }
+  }
+
+  private _reflowLargerAdjustViewport(newCols: number, newRows: number, countRemoved: number): void {
+    const nullCell = this.getNullCell(DEFAULT_ATTR_DATA);
+    // Adjust viewport based on number of items removed
+    let viewportAdjustments = countRemoved;
+    while (viewportAdjustments-- > 0) {
+      if (this.ybase === 0) {
+        if (this.y > 0) {
+          this.y--;
+        }
+        if (this.lines.length < newRows) {
+          // Add an extra row at the bottom of the viewport
+          this.lines.push(new BufferLine(newCols, nullCell));
+        }
+      } else {
+        if (this.ydisp === this.ybase) {
+          this.ydisp--;
+        }
+        this.ybase--;
+      }
+    }
+    this.savedY = Math.max(this.savedY - countRemoved, 0);
+  }
+
+  private _reflowSmaller(newCols: number, newRows: number): void {
+    const nullCell = this.getNullCell(DEFAULT_ATTR_DATA);
+    // Gather all BufferLines that need to be inserted into the Buffer here so that they can be
+    // batched up and only committed once
+    const toInsert = [];
+    let countToInsert = 0;
+    // Go backwards as many lines may be trimmed and this will avoid considering them
+    for (let y = this.lines.length - 1; y >= 0; y--) {
+      // Check whether this line is a problem
+      let nextLine = this.lines.get(y) as BufferLine;
+      if (!nextLine || !nextLine.isWrapped && nextLine.getTrimmedLength() <= newCols) {
+        continue;
+      }
+
+      // Gather wrapped lines and adjust y to be the starting line
+      const wrappedLines: BufferLine[] = [nextLine];
+      while (nextLine.isWrapped && y > 0) {
+        nextLine = this.lines.get(--y) as BufferLine;
+        wrappedLines.unshift(nextLine);
+      }
+
+      // If these lines contain the cursor don't touch them, the program will handle fixing up
+      // wrapped lines with the cursor
+      const absoluteY = this.ybase + this.y;
+      if (absoluteY >= y && absoluteY < y + wrappedLines.length) {
+        continue;
+      }
+
+      const lastLineLength = wrappedLines[wrappedLines.length - 1].getTrimmedLength();
+      const destLineLengths = reflowSmallerGetNewLineLengths(wrappedLines, this._cols, newCols);
+      const linesToAdd = destLineLengths.length - wrappedLines.length;
+      let trimmedLines: number;
+      if (this.ybase === 0 && this.y !== this.lines.length - 1) {
+        // If the top section of the buffer is not yet filled
+        trimmedLines = Math.max(0, this.y - this.lines.maxLength + linesToAdd);
+      } else {
+        trimmedLines = Math.max(0, this.lines.length - this.lines.maxLength + linesToAdd);
+      }
+
+      // Add the new lines
+      const newLines: BufferLine[] = [];
+      for (let i = 0; i < linesToAdd; i++) {
+        const newLine = this.getBlankLine(DEFAULT_ATTR_DATA, true) as BufferLine;
+        newLines.push(newLine);
+      }
+      if (newLines.length > 0) {
+        toInsert.push({
+          // countToInsert here gets the actual index, taking into account other inserted items.
+          // using this we can iterate through the list forwards
+          start: y + wrappedLines.length + countToInsert,
+          newLines
+        });
+        countToInsert += newLines.length;
+      }
+      wrappedLines.push(...newLines);
+
+      // Copy buffer data to new locations, this needs to happen backwards to do in-place
+      let destLineIndex = destLineLengths.length - 1; // Math.floor(cellsNeeded / newCols);
+      let destCol = destLineLengths[destLineIndex]; // cellsNeeded % newCols;
+      if (destCol === 0) {
+        destLineIndex--;
+        destCol = destLineLengths[destLineIndex];
+      }
+      let srcLineIndex = wrappedLines.length - linesToAdd - 1;
+      let srcCol = lastLineLength;
+      while (srcLineIndex >= 0) {
+        const cellsToCopy = Math.min(srcCol, destCol);
+        wrappedLines[destLineIndex].copyCellsFrom(wrappedLines[srcLineIndex], srcCol - cellsToCopy, destCol - cellsToCopy, cellsToCopy, true);
+        destCol -= cellsToCopy;
+        if (destCol === 0) {
+          destLineIndex--;
+          destCol = destLineLengths[destLineIndex];
+        }
+        srcCol -= cellsToCopy;
+        if (srcCol === 0) {
+          srcLineIndex--;
+          const wrappedLinesIndex = Math.max(srcLineIndex, 0);
+          srcCol = getWrappedLineTrimmedLength(wrappedLines, wrappedLinesIndex, this._cols);
+        }
+      }
+
+      // Null out the end of the line ends if a wide character wrapped to the following line
+      for (let i = 0; i < wrappedLines.length; i++) {
+        if (destLineLengths[i] < newCols) {
+          wrappedLines[i].setCell(destLineLengths[i], nullCell);
+        }
+      }
+
+      // Adjust viewport as needed
+      let viewportAdjustments = linesToAdd - trimmedLines;
+      while (viewportAdjustments-- > 0) {
+        if (this.ybase === 0) {
+          if (this.y < newRows - 1) {
+            this.y++;
+            this.lines.pop();
+          } else {
+            this.ybase++;
+            this.ydisp++;
+          }
+        } else {
+          // Ensure ybase does not exceed its maximum value
+          if (this.ybase < Math.min(this.lines.maxLength, this.lines.length + countToInsert) - newRows) {
+            if (this.ybase === this.ydisp) {
+              this.ydisp++;
+            }
+            this.ybase++;
+          }
+        }
+      }
+      this.savedY = Math.min(this.savedY + linesToAdd, this.ybase + newRows - 1);
+    }
+
+    // Rearrange lines in the buffer if there are any insertions, this is done at the end rather
+    // than earlier so that it's a single O(n) pass through the buffer, instead of O(n^2) from many
+    // costly calls to CircularList.splice.
+    if (toInsert.length > 0) {
+      // Record buffer insert events and then play them back backwards so that the indexes are
+      // correct
+      const insertEvents: IInsertEvent[] = [];
+
+      // Record original lines so they don't get overridden when we rearrange the list
+      const originalLines: BufferLine[] = [];
+      for (let i = 0; i < this.lines.length; i++) {
+        originalLines.push(this.lines.get(i) as BufferLine);
+      }
+      const originalLinesLength = this.lines.length;
+
+      let originalLineIndex = originalLinesLength - 1;
+      let nextToInsertIndex = 0;
+      let nextToInsert = toInsert[nextToInsertIndex];
+      this.lines.length = Math.min(this.lines.maxLength, this.lines.length + countToInsert);
+      let countInsertedSoFar = 0;
+      for (let i = Math.min(this.lines.maxLength - 1, originalLinesLength + countToInsert - 1); i >= 0; i--) {
+        if (nextToInsert && nextToInsert.start > originalLineIndex + countInsertedSoFar) {
+          // Insert extra lines here, adjusting i as needed
+          for (let nextI = nextToInsert.newLines.length - 1; nextI >= 0; nextI--) {
+            this.lines.set(i--, nextToInsert.newLines[nextI]);
+          }
+          i++;
+
+          // Create insert events for later
+          insertEvents.push({
+            index: originalLineIndex + 1,
+            amount: nextToInsert.newLines.length
+          });
+
+          countInsertedSoFar += nextToInsert.newLines.length;
+          nextToInsert = toInsert[++nextToInsertIndex];
+        } else {
+          this.lines.set(i, originalLines[originalLineIndex--]);
+        }
+      }
+
+      // Update markers
+      let insertCountEmitted = 0;
+      for (let i = insertEvents.length - 1; i >= 0; i--) {
+        insertEvents[i].index += insertCountEmitted;
+        this.lines.onInsertEmitter.fire(insertEvents[i]);
+        insertCountEmitted += insertEvents[i].amount;
+      }
+      const amountToTrim = Math.max(0, originalLinesLength + countToInsert - this.lines.maxLength);
+      if (amountToTrim > 0) {
+        this.lines.onTrimEmitter.fire(amountToTrim);
+      }
+    }
+  }
+
+  // private _reflowSmallerGetLinesNeeded()
+
+  /**
+   * Translates a string index back to a BufferIndex.
+   * To get the correct buffer position the string must start at `startCol` 0
+   * (default in translateBufferLineToString).
+   * The method also works on wrapped line strings given rows were not trimmed.
+   * The method operates on the CharData string length, there are no
+   * additional content or boundary checks. Therefore the string and the buffer
+   * should not be altered in between.
+   * TODO: respect trim flag after fixing #1685
+   * @param lineIndex line index the string was retrieved from
+   * @param stringIndex index within the string
+   * @param startCol column offset the string was retrieved from
+   */
+  public stringIndexToBufferIndex(lineIndex: number, stringIndex: number, trimRight: boolean = false): BufferIndex {
+    while (stringIndex) {
+      const line = this.lines.get(lineIndex);
+      if (!line) {
+        return [-1, -1];
+      }
+      const length = (trimRight) ? line.getTrimmedLength() : line.length;
+      for (let i = 0; i < length; ++i) {
+        if (line.get(i)[CHAR_DATA_WIDTH_INDEX]) {
+          // empty cells report a string length of 0, but get replaced
+          // with a whitespace in translateToString, thus replace with 1
+          stringIndex -= line.get(i)[CHAR_DATA_CHAR_INDEX].length || 1;
+        }
+        if (stringIndex < 0) {
+          return [lineIndex, i];
+        }
+      }
+      lineIndex++;
+    }
+    return [lineIndex, 0];
+  }
+
+  /**
+   * Translates a buffer line to a string, with optional start and end columns.
+   * Wide characters will count as two columns in the resulting string. This
+   * function is useful for getting the actual text underneath the raw selection
+   * position.
+   * @param line The line being translated.
+   * @param trimRight Whether to trim whitespace to the right.
+   * @param startCol The column to start at.
+   * @param endCol The column to end at.
+   */
+  public translateBufferLineToString(lineIndex: number, trimRight: boolean, startCol: number = 0, endCol?: number): string {
+    const line = this.lines.get(lineIndex);
+    if (!line) {
+      return '';
+    }
+    return line.translateToString(trimRight, startCol, endCol);
+  }
+
+  public getWrappedRangeForLine(y: number): { first: number, last: number } {
+    let first = y;
+    let last = y;
+    // Scan upwards for wrapped lines
+    while (first > 0 && this.lines.get(first)!.isWrapped) {
+      first--;
+    }
+    // Scan downwards for wrapped lines
+    while (last + 1 < this.lines.length && this.lines.get(last + 1)!.isWrapped) {
+      last++;
+    }
+    return { first, last };
+  }
+
+  /**
+   * Setup the tab stops.
+   * @param i The index to start setting up tab stops from.
+   */
+  public setupTabStops(i?: number): void {
+    if (i !== null && i !== undefined) {
+      if (!this.tabs[i]) {
+        i = this.prevStop(i);
+      }
+    } else {
+      this.tabs = {};
+      i = 0;
+    }
+
+    for (; i < this._cols; i += this._optionsService.options.tabStopWidth) {
+      this.tabs[i] = true;
+    }
+  }
+
+  /**
+   * Move the cursor to the previous tab stop from the given position (default is current).
+   * @param x The position to move the cursor to the previous tab stop.
+   */
+  public prevStop(x?: number): number {
+    if (x === null || x === undefined) {
+      x = this.x;
+    }
+    while (!this.tabs[--x] && x > 0);
+    return x >= this._cols ? this._cols - 1 : x < 0 ? 0 : x;
+  }
+
+  /**
+   * Move the cursor one tab stop forward from the given position (default is current).
+   * @param x The position to move the cursor one tab stop forward.
+   */
+  public nextStop(x?: number): number {
+    if (x === null || x === undefined) {
+      x = this.x;
+    }
+    while (!this.tabs[++x] && x < this._cols);
+    return x >= this._cols ? this._cols - 1 : x < 0 ? 0 : x;
+  }
+
+  public addMarker(y: number): Marker {
+    const marker = new Marker(y);
+    this.markers.push(marker);
+    marker.register(this.lines.onTrim(amount => {
+      marker.line -= amount;
+      // The marker should be disposed when the line is trimmed from the buffer
+      if (marker.line < 0) {
+        marker.dispose();
+      }
+    }));
+    marker.register(this.lines.onInsert(event => {
+      if (marker.line >= event.index) {
+        marker.line += event.amount;
+      }
+    }));
+    marker.register(this.lines.onDelete(event => {
+      // Delete the marker if it's within the range
+      if (marker.line >= event.index && marker.line < event.index + event.amount) {
+        marker.dispose();
+      }
+
+      // Shift the marker if it's after the deleted range
+      if (marker.line > event.index) {
+        marker.line -= event.amount;
+      }
+    }));
+    marker.register(marker.onDispose(() => this._removeMarker(marker)));
+    return marker;
+  }
+
+  private _removeMarker(marker: Marker): void {
+    this.markers.splice(this.markers.indexOf(marker), 1);
+  }
+
+  public iterator(trimRight: boolean, startIndex?: number, endIndex?: number, startOverscan?: number, endOverscan?: number): IBufferStringIterator {
+    return new BufferStringIterator(this, trimRight, startIndex, endIndex, startOverscan, endOverscan);
+  }
+}
+
+/**
+ * Iterator to get unwrapped content strings from the buffer.
+ * The iterator returns at least the string data between the borders
+ * `startIndex` and `endIndex` (exclusive) and will expand the lines
+ * by `startOverscan` to the top and by `endOverscan` to the bottom,
+ * if no new line was found in between.
+ * It will never read/return string data beyond `startIndex - startOverscan`
+ * or `endIndex + endOverscan`. Therefore the first and last line might be truncated.
+ * It is possible to always get the full string for the first and last line as well
+ * by setting the overscan values to the actual buffer length. This not recommended
+ * since it might return the whole buffer within a single string in a worst case scenario.
+ */
+export class BufferStringIterator implements IBufferStringIterator {
+  private _current: number;
+
+  constructor (
+    private _buffer: IBuffer,
+    private _trimRight: boolean,
+    private _startIndex: number = 0,
+    private _endIndex: number = _buffer.lines.length,
+    private _startOverscan: number = 0,
+    private _endOverscan: number = 0
+  ) {
+    if (this._startIndex < 0) {
+      this._startIndex = 0;
+    }
+    if (this._endIndex > this._buffer.lines.length) {
+      this._endIndex = this._buffer.lines.length;
+    }
+    this._current = this._startIndex;
+  }
+
+  public hasNext(): boolean {
+    return this._current < this._endIndex;
+  }
+
+  public next(): IBufferStringIteratorResult {
+    const range = this._buffer.getWrappedRangeForLine(this._current);
+    // limit search window to overscan value at both borders
+    if (range.first < this._startIndex - this._startOverscan) {
+      range.first = this._startIndex - this._startOverscan;
+    }
+    if (range.last > this._endIndex + this._endOverscan) {
+      range.last = this._endIndex + this._endOverscan;
+    }
+    // limit to current buffer length
+    range.first = Math.max(range.first, 0);
+    range.last = Math.min(range.last, this._buffer.lines.length);
+    let result = '';
+    for (let i = range.first; i <= range.last; ++i) {
+      result += this._buffer.translateBufferLineToString(i, this._trimRight);
+    }
+    this._current = range.last + 1;
+    return {range: range, content: result};
+  }
+}