Track source locations in the AST

These are stored as character offsets for the original input (`src`) as well as the printed output (`dst`)

packages/tailwindcss/src/ast.ts

@@ -1,6 +1,7 @@
 import { Polyfills } from '.'
 import { parseAtRule } from './css-parser'
 import type { DesignSystem } from './design-system'
+import type { Source, SourceLocation } from './source-maps/source'
 import { Theme, ThemeOptions } from './theme'
 import { DefaultMap } from './utils/default-map'
 import { extractUsedVariables } from './utils/variables'
@@ -12,6 +13,9 @@ export type StyleRule = {
   kind: 'rule'
   selector: string
   nodes: AstNode[]
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type AtRule = {
@@ -19,6 +23,9 @@ export type AtRule = {
   name: string
   params: string
   nodes: AstNode[]
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Declaration = {
@@ -26,22 +33,34 @@ export type Declaration = {
   property: string
   value: string | undefined
   important: boolean
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Comment = {
   kind: 'comment'
   value: string
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Context = {
   kind: 'context'
   context: Record<string, string | boolean>
   nodes: AstNode[]
+
+  src?: undefined
+  dst?: undefined
 }
 
 export type AtRoot = {
   kind: 'at-root'
   nodes: AstNode[]
+
+  src?: undefined
+  dst?: undefined
 }
 
 export type Rule = StyleRule | AtRule

packages/tailwindcss/src/source-maps/source.ts

@@ -0,0 +1,27 @@
+/**
+ * The source code for one or more nodes in the AST
+ *
+ * This generally corresponds to a stylesheet
+ */
+export interface Source {
+  /**
+   * The path to the file that contains the referenced source code
+   *
+   * If this references the *output* source code, this is `null`.
+   */
+  file: string | null
+
+  /**
+   * The referenced source code
+   */
+  code: string
+}
+
+/**
+ * The file and offsets within it that this node covers
+ *
+ * This can represent either:
+ * - A location in the original CSS which caused this node to be created
+ * - A location in the output CSS where this node resides
+ */
+export type SourceLocation = [source: Source, start: number, end: number]