Add getPosAtLineNumber

packages/common/lib/ts-morph-common.d.ts

@@ -966,6 +966,7 @@ export declare class StringUtils {
     static endsWithNewLine(str: string | undefined): boolean;
     static insertAtLastNonWhitespace(str: string, insertText: string): string;
     static getLineNumberAtPos(str: string, pos: number): number;
+    static getPosAtLineNumber(str: string, line: number): number;
     static getLengthFromLineStartAtPos(str: string, pos: number): number;
     static getLineStartFromPos(str: string, pos: number): number;
     static getLineEndFromPos(str: string, pos: number): number;

packages/common/src/tests/utils/stringUtilsTests.ts

@@ -39,6 +39,57 @@ describe(nameof(StringUtils), () => {
         });
     });
 
+    describe(nameof(StringUtils.getPosAtLineNumber), () => {
+        it("should throw if providing a negative line number", () => {
+            expect(() => StringUtils.getPosAtLineNumber("", -1)).to.throw(errors.ArgumentOutOfRangeError);
+        });
+
+        it("should not throw if providing a line number the amount of lines", () => {
+            expect(() => StringUtils.getPosAtLineNumber("", 1)).to.not.throw();
+        });
+
+        it("should throw if providing a line number greater than the length + 1", () => {
+            expect(() => StringUtils.getPosAtLineNumber("", 2)).to.throw(errors.ArgumentOutOfRangeError);
+        });
+
+        function doTest(newLineType: string) {
+            let str = `testing${newLineType}this${newLineType}out${newLineType}`;
+            const pos = str.length;
+            str += `more and more${newLineType}and more`;
+            expect(StringUtils.getPosAtLineNumber(str, 4)).to.equal(pos);
+        }
+
+        it("should get the pos for the specified line number when using \\n newlines", () => {
+            doTest("\n");
+        });
+
+        it("should get the pos for the specified line number when using \\r\\n newlines", () => {
+            doTest("\r\n");
+        });
+
+        it("should get the pos for the specified line number when right after the newline when mixing newlines", () => {
+            let str = "testing\r\nthis\nout\nmore\r\nandmore\n";
+            const pos = str.length;
+            str += "out\r\nmore and more";
+            expect(StringUtils.getPosAtLineNumber(str, 6)).to.equal(pos);
+        });
+
+        function testSymmetry(newLineType: string) {
+            let str = `testing${newLineType}this${newLineType}out`;
+            const posAtLine = StringUtils.getPosAtLineNumber(str, 2);
+            const lineAtPos = StringUtils.getLineNumberAtPos(str, posAtLine);
+            expect(lineAtPos).to.equal(2);
+        }
+
+        it("should be symmetric with getLineNumberAtPos when using \\n newlines", () => {
+            testSymmetry("\n");
+        });
+
+        it("should be symmetric with getLineNumberAtPos when using \\r\\n newlines", () => {
+            testSymmetry("\r\n");
+        });
+    });
+
     describe(nameof(StringUtils.getLengthFromLineStartAtPos), () => {
         it("should throw if providing a negative pos", () => {
             expect(() => StringUtils.getLengthFromLineStartAtPos("", -1)).to.throw(errors.ArgumentOutOfRangeError);

packages/common/src/utils/StringUtils.ts

@@ -85,6 +85,18 @@ export class StringUtils {
         return count + 1; // convert count to line number
     }
 
+    static getPosAtLineNumber(str: string, line: number) {
+        const lines = str.split('\n');
+        errors.throwIfOutOfRange(line, [1, lines.length], nameof(line));
+        let count = 0;
+
+        for (let i = 0; i < line - 1; i++) { // line number is 1-indexed
+            count += lines[i].length + 1; // include newline
+        }
+
+        return count; // convert count to pos
+    }
+
     static getLengthFromLineStartAtPos(str: string, pos: number) {
         errors.throwIfOutOfRange(pos, [0, str.length], nameof(pos));
         return pos - StringUtils.getLineStartFromPos(str, pos);

packages/ts-morph/lib/ts-morph.d.ts

@@ -7203,6 +7203,12 @@ export declare class SourceFile extends SourceFileBase<ts.SourceFile> {
             line: number;
             column: number;
         };
+    /**
+     * Gets the position (1-indexed) at the provided line and column number.
+     * @param line - Line number in the source file.
+     * @param col - Column number in the source file.
+     */
+    getPosAtLineAndColumn(line: number, col: number): number;
     /**
      * Gets the character count from the start of the line to the provided position.
      * @param pos - Position.

packages/ts-morph/src/compiler/ast/module/SourceFile.ts

@@ -162,7 +162,7 @@ export class SourceFile extends SourceFileBase<ts.SourceFile> {
     }
 
     /**
-     * Gets the line and column number at the provided position (1-indexed).
+     * Gets the line and column number (1-indexed) at the provided position.
      * @param pos - Position in the source file.
      */
     getLineAndColumnAtPos(pos: number) {
@@ -173,6 +173,16 @@ export class SourceFile extends SourceFileBase<ts.SourceFile> {
         };
     }
 
+    /**
+     * Gets the position at the provided line and column number (1-indexed).
+     * @param line - Line number in the source file.
+     * @param col - Column number in the source file.
+     */
+    getPosAtLineAndColumn(line: number, col: number) {
+        const fullText = this.getFullText();
+        return StringUtils.getPosAtLineNumber(fullText, line) + col;
+    }
+
     /**
      * Gets the character count from the start of the line to the provided position.
      * @param pos - Position.