From 617d33c9ae2fcaaadab27fbc079a52a9c782a15d Mon Sep 17 00:00:00 2001
From: Dylan Piercey <dpiercey@ebay.com>
Date: Fri, 29 Jul 2022 13:35:24 -0700
Subject: [PATCH] feat: expose position / location / line internal apis

---
 .changeset/proud-worms-unite.md |  5 +++
 src/core/Parser.ts              | 17 +++++---
 src/index.ts                    |  3 ++
 src/util/util.ts                | 72 +++++++++++++++++++++------------
 4 files changed, 66 insertions(+), 31 deletions(-)
 create mode 100644 .changeset/proud-worms-unite.md

diff --git a/.changeset/proud-worms-unite.md b/.changeset/proud-worms-unite.md
new file mode 100644
index 00000000..c8e72eca
--- /dev/null
+++ b/.changeset/proud-worms-unite.md
@@ -0,0 +1,5 @@
+---
+"htmljs-parser": minor
+---
+
+Expose some apis for generating position and location information.
diff --git a/src/core/Parser.ts b/src/core/Parser.ts
index 8b41d45c..4e6a1bd2 100644
--- a/src/core/Parser.ts
+++ b/src/core/Parser.ts
@@ -6,8 +6,8 @@ import {
   Range,
   ParserOptions as Options,
   getLines,
-  getLoc,
-  getPos,
+  getLocation,
+  getPosition,
   ErrorCode,
 } from "../internal";
 
@@ -53,12 +53,19 @@ export class Parser {
     return this.data.slice(range.start, range.end);
   }
 
-  positionAt(index: number) {
-    return getPos(this.lines || (this.lines = getLines(this.data)), 0, index);
+  positionAt(offset: number) {
+    return getPosition(
+      this.lines || (this.lines = getLines(this.data)),
+      offset
+    );
   }
 
   locationAt(range: Range) {
-    return getLoc(this.lines || (this.lines = getLines(this.data)), range);
+    return getLocation(
+      this.lines || (this.lines = getLines(this.data)),
+      range.start,
+      range.end
+    );
   }
 
   enterState<P extends Meta>(state: StateDefinition<P>): P {
diff --git a/src/index.ts b/src/index.ts
index a9baf194..73fab708 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,6 +2,9 @@ import { type ParserOptions, type Range, Parser } from "./internal";
 export {
   TagType,
   ErrorCode,
+  getLines,
+  getLocation,
+  getPosition,
   type ParserOptions as Handlers,
   type Position,
   type Location,
diff --git a/src/util/util.ts b/src/util/util.ts
index 7a00c9b7..65a96bcf 100644
--- a/src/util/util.ts
+++ b/src/util/util.ts
@@ -1,5 +1,5 @@
 import { CODE, type Parser } from "../internal";
-import { ErrorCode, Location, Position, Range } from "./constants";
+import { ErrorCode, Location, Position } from "./constants";
 
 export function isWhitespaceCode(code: number) {
   // For all practical purposes, the space character (32) and all the
@@ -9,37 +9,33 @@ export function isWhitespaceCode(code: number) {
   return code <= CODE.SPACE;
 }
 
-export function getLoc(lines: number[], range: Range): Location {
-  const start = getPos(lines, 0, range.start);
+/**
+ * Given a source code line offsets, a start offset and an end offset, returns a Location object with line & character information for the start and end offsets.
+ */
+export function getLocation(
+  lines: number[],
+  startOffset: number,
+  endOffset: number
+): Location {
+  const start = getPosition(lines, startOffset);
   const end =
-    range.start === range.end ? start : getPos(lines, start.line, range.end);
+    startOffset === endOffset
+      ? start
+      : getPosAfterLine(lines, start.line, endOffset);
   return { start, end };
 }
 
-export function getPos(
-  lines: number[],
-  startLine: number,
-  index: number
-): Position {
-  let max = lines.length - 1;
-  let line = startLine;
-
-  while (line < max) {
-    const mid = (1 + line + max) >>> 1;
-
-    if (lines[mid] <= index) {
-      line = mid;
-    } else {
-      max = mid - 1;
-    }
-  }
-
-  return {
-    line,
-    character: index - lines[line],
-  };
+/**
+ * Given a source code line offsets and an offset, returns a Position object with line & character information.
+ */
+export function getPosition(lines: number[], offset: number): Position {
+  return getPosAfterLine(lines, 0, offset);
 }
 
+/**
+ * Scan through some source code and generate an array of offsets for each newline.
+ * Useful for generating line/column information for source code.
+ */
 export function getLines(src: string) {
   const lines = [0];
   for (let i = 0; i < src.length; i++) {
@@ -71,3 +67,27 @@ export function htmlEOF(this: Parser) {
     }
   }
 }
+
+function getPosAfterLine(
+  lines: number[],
+  startLine: number,
+  index: number
+): Position {
+  let max = lines.length - 1;
+  let line = startLine;
+
+  while (line < max) {
+    const mid = (1 + line + max) >>> 1;
+
+    if (lines[mid] <= index) {
+      line = mid;
+    } else {
+      max = mid - 1;
+    }
+  }
+
+  return {
+    line,
+    character: index - lines[line],
+  };
+}