v3: Don't count seq indicator as part of indent.

emitterc.go

@@ -225,6 +225,15 @@ func yaml_emitter_append_tag_directive(emitter *yaml_emitter_t, value *yaml_tag_
 	return true
 }
 
+// Don't count the sequenceIndicator as part of sequence indentation.
+// This maintains sequence indentation consistency with gopkg.in/yaml.v2
+// (https://pkg.go.dev/gopkg.in/yaml.v2#readme-api-documentation)
+// and conforms to the YAML 1.2 spec comment
+//   > both the “-” indicator and the following spaces are considered
+//   > to be part of the indentation of the nested collection.
+// at https://yaml.org/spec/1.2/spec.html#id2772075
+const lenSequenceIndicator = len(`- `)
+
 // Increase the indentation level.
 func yaml_emitter_increase_indent(emitter *yaml_emitter_t, flow, indentless bool) bool {
 	emitter.indents = append(emitter.indents, emitter.indent)
@@ -235,13 +244,10 @@ func yaml_emitter_increase_indent(emitter *yaml_emitter_t, flow, indentless bool
 			emitter.indent = 0
 		}
 	} else if !indentless {
-		// [Go] This was changed so that indentations are more regular.
-		if emitter.states[len(emitter.states)-1] == yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE {
-			// The first indent inside a sequence will just skip the "- " indicator.
-			emitter.indent += 2
-		} else {
-			// Everything else aligns to the chosen indentation.
-			emitter.indent = emitter.best_indent*((emitter.indent+emitter.best_indent)/emitter.best_indent)
+		emitter.indent += emitter.best_indent
+		// If inside a block sequence item, discount the space taken by the indicator.
+		if emitter.best_indent > lenSequenceIndicator && emitter.states[len(emitter.states)-1] == yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE {
+			emitter.indent -= lenSequenceIndicator
 		}
 	}
 	return true
@@ -728,9 +734,13 @@ func yaml_emitter_emit_flow_mapping_value(emitter *yaml_emitter_t, event *yaml_e
 // Expect a block item node.
 func yaml_emitter_emit_block_sequence_item(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
 	if first {
+		originalIndent := emitter.indent
 		if !yaml_emitter_increase_indent(emitter, false, false) {
 			return false
 		}
+		if emitter.indent > originalIndent+lenSequenceIndicator {
+			emitter.indent -= lenSequenceIndicator
+		}
 	}
 	if event.typ == yaml_SEQUENCE_END_EVENT {
 		emitter.indent = emitter.indents[len(emitter.indents)-1]

encode_test.go

@@ -138,25 +138,25 @@ v: ""
 	}, {
 		map[string][]string{"v": []string{"A", "B"}}, `
 v:
-    - A
-    - B
+  - A
+  - B
 `,
 	}, {
 		map[string][]string{"v": []string{"A", "B\nC"}}, `
 v:
-    - A
-    - |-
-      B
-      C
+  - A
+  - |-
+    B
+    C
 `,
 	}, {
 		map[string][]interface{}{"v": []interface{}{"A", 1, map[string][]int{"B": []int{2, 3}}}}, `
 v:
-    - A
-    - 1
-    - B:
-        - 2
-        - 3
+  - A
+  - 1
+  - B:
+      - 2
+      - 3
 `,
 	}, {
 		map[string]interface{}{"a": map[interface{}]interface{}{"b": "c"}}, `
@@ -214,14 +214,14 @@ a: 1
 	}, {
 		&struct{ A []int }{[]int{1, 2}}, `
 a:
-    - 1
-    - 2
+  - 1
+  - 2
 `,
 	}, {
 		&struct{ A [2]int }{[2]int{1, 2}}, `
 a:
-    - 1
-    - 2
+  - 1
+  - 2
 `,
 	}, {
 		&struct {
@@ -530,8 +530,8 @@ true
 		map[string]interface{}{"a": map[string]interface{}{"b": []map[string]int{{"c": 1, "d": 2}}}}, `
 a:
     b:
-        - c: 1
-          d: 2
+      - c: 1
+        d: 2
 `,
 	},
 
@@ -713,7 +713,7 @@ var marshalerTests = []struct {
 	value interface{}
 }{
 	{"_:\n    hi: there\n", map[interface{}]interface{}{"hi": "there"}},
-	{"_:\n    - 1\n    - A\n", []interface{}{1, "A"}},
+	{"_:\n  - 1\n  - A\n", []interface{}{1, "A"}},
 	{"_: 10\n", 10},
 	{"_: null\n", nil},
 	{"_: BAR!\n", "BAR!"},
@@ -794,24 +794,24 @@ a:
     b:
         c: d
     e:
-        - 1
-        - 2
-        - 3
+      - 1
+      - 2
+      - 3
     f:
-        - g
-        - h
+      - g
+      - h
 `
 		indentEight = `
 a:
         b:
                 c: d
         e:
-                - 1
-                - 2
-                - 3
+              - 1
+              - 2
+              - 3
         f:
-                - g
-                - h
+              - g
+              - h
 `
 	)