feat(compiler-core): add parser transform for v-for directive (#65)

* feat(compiler-core): add parser transform for v-for directive

* fix: Include source location for expressions

* chore: remove comment

* refactor(compiler-core): extract hepler functions to utils

packages/compiler-core/src/utils.ts

@@ -0,0 +1,50 @@
+import { SourceLocation, Position } from './ast'
+
+export function getInnerRange(
+  loc: SourceLocation,
+  offset: number,
+  length?: number
+): SourceLocation {
+  const source = loc.source.substr(offset, length)
+  const newLoc: SourceLocation = {
+    source,
+    start: advancePositionBy(loc.start, loc.source, offset),
+    end: loc.end
+  }
+
+  if (length != null) {
+    newLoc.end = advancePositionBy(loc.start, loc.source, offset + length)
+  }
+
+  return newLoc
+}
+
+export function advancePositionBy(
+  pos: Position,
+  source: string,
+  numberOfCharacters: number
+): Position {
+  __DEV__ && assert(numberOfCharacters <= source.length)
+
+  const newPosition = {
+    ...pos
+  }
+
+  const str = source.slice(0, numberOfCharacters)
+  const lines = str.split(/\r?\n/)
+
+  newPosition.offset += numberOfCharacters
+  newPosition.line += lines.length - 1
+  newPosition.column =
+    lines.length === 1
+      ? pos.column + numberOfCharacters
+      : Math.max(1, lines.pop()!.length)
+
+  return newPosition
+}
+
+export function assert(condition: boolean, msg?: string) {
+  if (!condition) {
+    throw new Error(msg || `unexpected parser condition`)
+  }
+}