Fix the range of empty scalars (#231)

src/compose/compose-doc.ts

@@ -23,7 +23,7 @@ export function composeDoc(
 
   doc.contents = value
     ? composeNode(doc, value, props, onError)
-    : composeEmptyNode(doc, offset + props.length, props, onError)
+    : composeEmptyNode(doc, offset + props.length, start, null, props, onError)
 
   const re = resolveEnd(end, doc.contents.range[1], false, onError)
   if (re.comment) doc.comment = re.comment

src/compose/compose-node.ts

@@ -4,6 +4,7 @@ import type { FlowScalar, Token } from '../parse/tokens.js'
 import { composeCollection } from './compose-collection.js'
 import { composeScalar } from './compose-scalar.js'
 import { resolveEnd } from './resolve-end.js'
+import { emptyScalarPosition } from './util-empty-scalar-position.js'
 
 export interface Props {
   spaceBefore: boolean
@@ -52,10 +53,17 @@ export function composeNode(
 export function composeEmptyNode(
   doc: Document.Parsed,
   offset: number,
+  before: Token[] | undefined,
+  pos: number | null,
   { spaceBefore, comment, anchor, tagName }: Props,
   onError: (offset: number, message: string, warning?: boolean) => void
 ) {
-  const token: FlowScalar = { type: 'scalar', offset, indent: -1, source: '' }
+  const token: FlowScalar = {
+    type: 'scalar',
+    offset: emptyScalarPosition(offset, before, pos),
+    indent: -1,
+    source: ''
+  }
   const node = composeScalar(doc, token, anchor, tagName, onError)
   if (spaceBefore) node.spaceBefore = true
   if (comment) node.comment = comment

src/compose/resolve-block-map.ts

@@ -58,7 +58,7 @@ export function resolveBlockMap(
     const keyStart = offset
     const keyNode = key
       ? composeNode(doc, key, keyProps, onError)
-      : composeEmptyNode(doc, offset, keyProps, onError)
+      : composeEmptyNode(doc, offset, start, null, keyProps, onError)
     offset = keyNode.range[1]
 
     // value properties
@@ -88,7 +88,7 @@ export function resolveBlockMap(
       // value value
       const valueNode = value
         ? composeNode(doc, value, valueProps, onError)
-        : composeEmptyNode(doc, offset, valueProps, onError)
+        : composeEmptyNode(doc, offset, sep, null, valueProps, onError)
       offset = valueNode.range[1]
       const pair = new Pair(keyNode, valueNode)
       map.items.push(doc.schema.merge ? resolveMergePair(pair, onError) : pair)

src/compose/resolve-block-seq.ts

@@ -15,7 +15,7 @@ export function resolveBlockSeq(
   const seq = new YAMLSeq(doc.schema)
   seq.type = Type.SEQ
   if (anchor) doc.anchors.setAnchor(seq, anchor)
-  loop: for (const { start, value } of items) {
+  for (const { start, value } of items) {
     const props = resolveProps(
       doc,
       start,
@@ -40,7 +40,7 @@ export function resolveBlockSeq(
     }
     const node = value
       ? composeNode(doc, value, props, onError)
-      : composeEmptyNode(doc, offset, props, onError)
+      : composeEmptyNode(doc, offset, start, null, props, onError)
     offset = node.range[1]
     seq.items.push(node)
   }

src/compose/resolve-flow-collection.ts

@@ -49,11 +49,11 @@ export function resolveFlowCollection(
     return props
   }
 
-  function addItem() {
+  function addItem(pos: number) {
     if (value) {
       if (hasComment) value.comment = comment
     } else {
-      value = composeEmptyNode(doc, offset, getProps(), onError)
+      value = composeEmptyNode(doc, offset, fc.items, pos, getProps(), onError)
     }
     if (isMap || atExplicitKey) {
       const pair = key ? new Pair(key, value) : new Pair(value)
@@ -69,7 +69,8 @@ export function resolveFlowCollection(
     }
   }
 
-  for (const token of fc.items) {
+  for (let i = 0; i < fc.items.length; ++i) {
+    const token = fc.items[i]
     let isSourceToken = true
     switch (token.type) {
       case 'space':
@@ -162,7 +163,7 @@ export function resolveFlowCollection(
           key = value
           value = null
         } else {
-          key = composeEmptyNode(doc, offset, getProps(), onError)
+          key = composeEmptyNode(doc, offset, fc.items, i, getProps(), onError)
         }
         if (hasComment) {
           key.comment = comment
@@ -175,7 +176,7 @@ export function resolveFlowCollection(
         break
       }
       case 'comma':
-        if (key || value || anchor || tagName || atExplicitKey) addItem()
+        if (key || value || anchor || tagName || atExplicitKey) addItem(i)
         else
           onError(offset, `Unexpected , in flow ${isMap ? 'map' : 'sequence'}`)
         key = null
@@ -206,7 +207,8 @@ export function resolveFlowCollection(
     }
     if (isSourceToken) offset += (token as SourceToken).source.length
   }
-  if (key || value || anchor || tagName || atExplicitKey) addItem()
+  if (key || value || anchor || tagName || atExplicitKey)
+    addItem(fc.items.length)
 
   const expectedEnd = isMap ? '}' : ']'
   const [ce, ...ee] = fc.end

src/compose/util-empty-scalar-position.ts

@@ -0,0 +1,31 @@
+import type { Token } from '../parse/tokens.js'
+
+export function emptyScalarPosition(
+  offset: number,
+  before: Token[] | undefined,
+  pos: number | null
+) {
+  if (before) {
+    if (pos === null) pos = before.length
+    for (let i = pos - 1; i >= 0; --i) {
+      let st = before[i]
+      switch (st.type) {
+        case 'space':
+        case 'comment':
+        case 'newline':
+          offset -= st.source.length
+          continue
+      }
+
+      // Technically, an empty scalar is immediately after the last non-empty
+      // node, but it's more useful to place it after any whitespace.
+      st = before[++i]
+      while (st?.type === 'space') {
+        offset += st.source.length
+        st = before[++i]
+      }
+      break
+    }
+  }
+  return offset
+}

tests/doc/parse.js

@@ -456,10 +456,10 @@ test('comment between key & : in flow collection (eemeli/yaml#149)', () => {
   )
 })
 
-test('empty node should respect setOrigRanges()', () => {
+test('empty node position', () => {
   const doc = YAML.parseDocument('\r\na: # 123\r\n')
   const empty = doc.contents.items[0].value
-  expect(empty.range).toEqual([12, 12])
+  expect(empty.range).toEqual([5, 5])
 })
 
 test('parse an empty string as null', () => {