feat: Add stringKeys parse option (#581)

docs/03_options.md

@@ -29,6 +29,7 @@ Used by: `parse()`, `parseDocument()`, `parseAllDocuments()`, `new Composer()`,
 | lineCounter      | `LineCounter`                 |         | If set, newlines will be tracked, to allow for `lineCounter.linePos(offset)` to provide the `{ line, col }` positions within the input.                                    |
 | prettyErrors     | `boolean`                     | `true`  | Include line/col position in errors, along with an extract of the source string.                                                                                           |
 | strict           | `boolean`                     | `true`  | When parsing, do not ignore errors [required](#silencing-errors-and-warnings) by the YAML 1.2 spec, but caused by unambiguous content.                                     |
+| stringKeys       | `boolean`                     | `false` | Parse all mapping keys as strings. Treat all non-scalar keys as errors.                                                                                                    |
 | uniqueKeys       | `boolean ⎮ (a, b) => boolean` | `true`  | Whether key uniqueness is checked, or customised. If set to be a function, it will be passed two parsed nodes and should return a boolean value indicating their equality. |
 
 [bigint]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/BigInt

docs/08_errors.md

@@ -26,6 +26,7 @@ To identify errors for special handling, you should primarily use `code` to diff
 | ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `ALIAS_PROPS`            | Unlike scalars and collections, alias nodes cannot have an anchor or tag associated with it.                                                                                 |
 | `BAD_ALIAS`              | An alias identifier must be a non-empty sequence of valid characters.                                                                                                        |
+| `BAD_COLLECTION_TYPE`    | Explicit collection tag used on a collection type it does not support.                                                                                                       |
 | `BAD_DIRECTIVE`          | Only the `%YAML` and `%TAG` directives are supported, and they need to follow the specified structure.                                                                       |
 | `BAD_DQ_ESCAPE`          | Double-quotes strings may include `\` escaped content, but that needs to be valid.                                                                                           |
 | `BAD_INDENT`             | Indentation is important in YAML, and collection items need to all start at the same level. Block scalars are also picky about their leading content.                        |
@@ -36,12 +37,12 @@ To identify errors for special handling, you should primarily use `code` to diff
 | `DUPLICATE_KEY`          | Map keys must be unique. Use the `uniqueKeys` option to disable or customise this check when parsing.                                                                        |
 | `IMPOSSIBLE`             | This really should not happen. If you encounter this error code, please file a bug.                                                                                          |
 | `KEY_OVER_1024_CHARS`    | Due to legacy reasons, implicit keys must have their following `:` indicator after at most 1k characters.                                                                    |
-| `MISSING_ANCHOR`         | Aliases can only dereference anchors that are before them in the document.                                                                                                   |
 | `MISSING_CHAR`           | Some character or characters are missing here. See the error message for what you need to add.                                                                               |
 | `MULTILINE_IMPLICIT_KEY` | Implicit keys need to be on a single line. Does the input include a plain scalar with a `:` followed by whitespace, which is getting parsed as a map key?                    |
 | `MULTIPLE_ANCHORS`       | A node is only allowed to have one anchor.                                                                                                                                   |
 | `MULTIPLE_DOCS`          | A YAML stream may include multiple documents. If yours does, you'll need to use `parseAllDocuments()` to work with it.                                                       |
 | `MULTIPLE_TAGS`          | A node is only allowed to have one tag.                                                                                                                                      |
+| `NON_STRING_KEY`         | With the `stringKeys` option, all mapping keys must be strings                                                                                                               |
 | `TAB_AS_INDENT`          | Only spaces are allowed as indentation.                                                                                                                                      |
 | `TAG_RESOLVE_FAILED`     | Something went wrong when resolving a node's tag with the current schema.                                                                                                    |
 | `UNEXPECTED_TOKEN`       | A token was encountered in a place where it wasn't expected.                                                                                                                 |

src/compose/compose-node.ts

@@ -1,5 +1,6 @@
 import type { Directives } from '../doc/directives.js'
 import { Alias } from '../nodes/Alias.js'
+import { isScalar } from '../nodes/identity.js'
 import type { ParsedNode } from '../nodes/Node.js'
 import type { ParseOptions } from '../options.js'
 import type { FlowScalar, SourceToken, Token } from '../parse/cst.js'
@@ -36,6 +37,7 @@ export function composeNode(
   props: Props,
   onError: ComposeErrorHandler
 ) {
+  const atKey = ctx.atKey
   const { spaceBefore, comment, anchor, tag } = props
   let node: ParsedNode
   let isSrcToken = true
@@ -81,6 +83,16 @@ export function composeNode(
   }
   if (anchor && node.anchor === '')
     onError(anchor, 'BAD_ALIAS', 'Anchor cannot be an empty string')
+  if (
+    atKey &&
+    ctx.options.stringKeys &&
+    (!isScalar(node) ||
+      typeof node.value !== 'string' ||
+      (node.tag && node.tag !== 'tag:yaml.org,2002:str'))
+  ) {
+    const msg = 'With stringKeys, all keys must be strings'
+    onError(tag ?? token, 'NON_STRING_KEY', msg)
+  }
   if (spaceBefore) node.spaceBefore = true
   if (comment) {
     if (token.type === 'scalar' && token.source === '') node.comment = comment

src/compose/compose-scalar.ts

@@ -24,12 +24,15 @@ export function composeScalar(
         onError(tagToken, 'TAG_RESOLVE_FAILED', msg)
       )
     : null
-  const tag =
-    tagToken && tagName
-      ? findScalarTagByName(ctx.schema, value, tagName, tagToken, onError)
-      : token.type === 'scalar'
-        ? findScalarTagByTest(ctx, value, token, onError)
-        : ctx.schema[SCALAR]
+
+  let tag: ScalarTag
+  if (ctx.options.stringKeys && ctx.atKey) {
+    tag = ctx.schema[SCALAR]
+  } else if (tagName)
+    tag = findScalarTagByName(ctx.schema, value, tagName, tagToken!, onError)
+  else if (token.type === 'scalar')
+    tag = findScalarTagByTest(ctx, value, token, onError)
+  else tag = ctx.schema[SCALAR]
 
   let scalar: Scalar
   try {

src/doc/Document.ts

@@ -122,6 +122,7 @@ export class Document<
         logLevel: 'warn',
         prettyErrors: true,
         strict: true,
+        stringKeys: false,
         uniqueKeys: true,
         version: '1.2'
       },

src/errors.ts

@@ -18,6 +18,7 @@ export type ErrorCode =
   | 'MULTIPLE_ANCHORS'
   | 'MULTIPLE_DOCS'
   | 'MULTIPLE_TAGS'
+  | 'NON_STRING_KEY'
   | 'TAB_AS_INDENT'
   | 'TAG_RESOLVE_FAILED'
   | 'UNEXPECTED_TOKEN'

src/options.ts

@@ -48,6 +48,13 @@ export type ParseOptions = {
    */
   strict?: boolean
 
+  /**
+   * Parse all mapping keys as strings. Treat all non-scalar keys as errors.
+   *
+   * Default: `false`
+   */
+  stringKeys?: boolean
+
   /**
    * YAML requires map keys to be unique. By default, this is checked by
    * comparing scalar values with `===`; deep equality is not checked for

tests/doc/parse.ts

@@ -880,3 +880,39 @@ describe('CRLF line endings', () => {
     expect(res).toBe('foo bar')
   })
 })
+
+describe('stringKeys', () => {
+  test('success', () => {
+    const doc = YAML.parseDocument<any>(
+      source`
+        x: x
+        !!str y: y
+        42: 42
+        true: true
+        null: null
+        ~: ~
+        :
+      `,
+      { stringKeys: true }
+    )
+    expect(doc.contents.items).toMatchObject([
+      { key: { value: 'x' }, value: { value: 'x' } },
+      { key: { value: 'y' }, value: { value: 'y' } },
+      { key: { value: '42' }, value: { value: 42 } },
+      { key: { value: 'true' }, value: { value: true } },
+      { key: { value: 'null' }, value: { value: null } },
+      { key: { value: '~' }, value: { value: null } },
+      { key: { value: '' }, value: { value: null } }
+    ])
+  })
+
+  test('explicit non-string tag', () => {
+    const doc = YAML.parseDocument('!!int 42: 42', { stringKeys: true })
+    expect(doc.errors).toMatchObject([{ code: 'NON_STRING_KEY' }])
+  })
+
+  test('collection key', () => {
+    const doc = YAML.parseDocument('{ x, y }: 42', { stringKeys: true })
+    expect(doc.errors).toMatchObject([{ code: 'NON_STRING_KEY' }])
+  })
+})