Implement scroll by last line (#10057)

Author: rchiodo

news/2 Fixes/9116.md

@@ -0,0 +1 @@
+Remove whitespace from code before pushing to the interactive window

src/datascience-ui/common/index.ts

@@ -54,6 +54,37 @@ export function splitMultilineString(source: nbformat.MultilineString): string[]
     return [];
 }
 
+export function removeLinesFromFrontAndBack(code: string): string {
+    const lines = code.splitLines({ trim: false, removeEmptyEntries: false });
+    let foundNonEmptyLine = false;
+    let lastNonEmptyLine = -1;
+    let result: string[] = [];
+    parseForComments(
+        lines,
+        (_s, i) => {
+            result.push(lines[i]);
+            lastNonEmptyLine = i;
+        },
+        (s, i) => {
+            const trimmed = s.trim();
+            if (foundNonEmptyLine || trimmed) {
+                result.push(lines[i]);
+                foundNonEmptyLine = true;
+            }
+            if (trimmed) {
+                lastNonEmptyLine = i;
+            }
+        }
+    );
+
+    // Remove empty lines off the bottom too
+    if (lastNonEmptyLine < lines.length - 1) {
+        result = result.slice(0, result.length - (lines.length - 1 - lastNonEmptyLine));
+    }
+
+    return result.join('\n');
+}
+
 // Strip out comment lines from code
 export function stripComments(str: string): string {
     let result: string = '';

src/datascience-ui/history-react/redux/reducers/creation.ts

@@ -4,6 +4,7 @@
 import { Identifiers } from '../../../../client/datascience/constants';
 import { InteractiveWindowMessages } from '../../../../client/datascience/interactive-common/interactiveWindowTypes';
 import { ICell, IDataScienceExtraSettings } from '../../../../client/datascience/types';
+import { removeLinesFromFrontAndBack } from '../../../common';
 import { createCellVM, extractInputText, ICellViewModel, IMainState } from '../../../interactive-common/mainState';
 import { createPostableAction } from '../../../interactive-common/redux/postOffice';
 import { Helpers } from '../../../interactive-common/redux/reducers/helpers';
@@ -19,6 +20,14 @@ export namespace Creation {
         return true;
     }
 
+    function extractInputBlockText(cellVM: ICellViewModel, settings?: IDataScienceExtraSettings) {
+        // Use the base function first
+        const text = extractInputText(cellVM, settings);
+
+        // Then remove text on the front and back. We only do this for the interactive window
+        return removeLinesFromFrontAndBack(text);
+    }
+
     export function alterCellVM(cellVM: ICellViewModel, settings?: IDataScienceExtraSettings, visible?: boolean, expanded?: boolean): ICellViewModel {
         if (cellVM.cell.data.cell_type === 'code') {
             // If we are already in the correct state, return back our initial cell vm
@@ -41,13 +50,13 @@ export namespace Creation {
             if (cellVM.inputBlockOpen !== expanded && cellVM.inputBlockCollapseNeeded && cellVM.inputBlockShow) {
                 if (expanded) {
                     // Expand the cell
-                    const newText = extractInputText(cellVM, settings);
+                    const newText = extractInputBlockText(cellVM, settings);
 
                     newCellVM.inputBlockOpen = true;
                     newCellVM.inputBlockText = newText;
                 } else {
                     // Collapse the cell
-                    let newText = extractInputText(cellVM, settings);
+                    let newText = extractInputBlockText(cellVM, settings);
                     if (newText.length > 0) {
                         newText = newText.split('\n', 1)[0];
                         newText = newText.slice(0, 255); // Slice to limit length, slicing past length is fine

src/test/datascience/cellFactory.unit.test.ts

@@ -3,7 +3,7 @@
 'use strict';
 import { assert } from 'chai';
 import { generateCells } from '../../client/datascience/cellFactory';
-import { stripComments } from '../../datascience-ui/common';
+import { removeLinesFromFrontAndBack, stripComments } from '../../datascience-ui/common';
 
 // tslint:disable: max-func-body-length
 suite('Data Science CellFactory', () => {
@@ -150,4 +150,51 @@ class Pizza(object):
         nonComments = stripComments(multilineQuoteInFunc);
         assert.equal(nonComments.splitLines().length, 6, 'Splitting quote in func wrong number of lines');
     });
+
+    test('Line removal', () => {
+        const entry1 = `# %% CELL
+
+first line`;
+        const expected1 = `# %% CELL
+first line`;
+        const entry2 = `# %% CELL
+
+first line
+
+`;
+        const expected2 = `# %% CELL
+first line`;
+        const entry3 = `# %% CELL
+
+first line
+
+second line
+
+`;
+        const expected3 = `# %% CELL
+first line
+
+second line`;
+
+        const entry4 = `
+
+if (foo):
+    print('stuff')
+
+print('some more')
+
+`;
+        const expected4 = `if (foo):
+    print('stuff')
+
+print('some more')`;
+        let removed = removeLinesFromFrontAndBack(entry1);
+        assert.equal(removed, expected1);
+        removed = removeLinesFromFrontAndBack(entry2);
+        assert.equal(removed, expected2);
+        removed = removeLinesFromFrontAndBack(entry3);
+        assert.equal(removed, expected3);
+        removed = removeLinesFromFrontAndBack(entry4);
+        assert.equal(removed, expected4);
+    });
 });