hclwrite: Generate multi-line objects and maps

The previous syntax for object and map values was a single line of
key-value pairs. For example:

  object = { bar = 5, baz = true, foo = "foo" }

This is very compact, but in practice for many HCL values, less readable
and less common than a multi-line object format. This commit changes the
generated output from hclwrite to one line per attribute.

Examples of the new format:

  // Empty object/map is a single line
  a = {}

  // Single-value object/map has the attribute on a separate line
  b = {
    bar = 5
  }

  // Multi-value object/map has one line per attribute
  c = {
    bar = 5
    baz = true
  }

hclwrite/examples_test.go

@@ -48,9 +48,13 @@ func Example_generateFromScratch() {
 	// Output:
 	// string = "foo"
 	//
-	// object = { bar = 5, baz = true, foo = "foo" }
+	// object = {
-	// bool   = false
+	//   bar = 5
-	// path   = env.PATH
+	//   baz = true
+	//   foo = "foo"
+	// }
+	// bool = false
+	// path = env.PATH
 	//
 	// foo {
 	//   hello = "world"

hclwrite/generate.go

@@ -119,15 +119,15 @@ func appendTokensForValue(val cty.Value, toks Tokens) Tokens {
 			Type:  hclsyntax.TokenOBrace,
 			Bytes: []byte{'{'},
 		})
+		if val.LengthInt() > 0 {
+			toks = append(toks, &Token{
+				Type:  hclsyntax.TokenNewline,
+				Bytes: []byte{'\n'},
+			})
+		}
 
 		i := 0
 		for it := val.ElementIterator(); it.Next(); {
-			if i > 0 {
-				toks = append(toks, &Token{
-					Type:  hclsyntax.TokenComma,
-					Bytes: []byte{','},
-				})
-			}
 			eKey, eVal := it.Element()
 			if hclsyntax.ValidIdentifier(eKey.AsString()) {
 				toks = append(toks, &Token{
@@ -142,6 +142,10 @@ func appendTokensForValue(val cty.Value, toks Tokens) Tokens {
 				Bytes: []byte{'='},
 			})
 			toks = appendTokensForValue(eVal, toks)
+			toks = append(toks, &Token{
+				Type:  hclsyntax.TokenNewline,
+				Bytes: []byte{'\n'},
+			})
 			i++
 		}
 

hclwrite/generate_test.go

@@ -340,10 +340,14 @@ func TestTokensForValue(t *testing.T) {
 					Type:  hclsyntax.TokenOBrace,
 					Bytes: []byte(`{`),
 				},
+				{
+					Type:  hclsyntax.TokenNewline,
+					Bytes: []byte("\n"),
+				},
 				{
 					Type:         hclsyntax.TokenIdent,
 					Bytes:        []byte(`foo`),
-					SpacesBefore: 1,
+					SpacesBefore: 2,
 				},
 				{
 					Type:         hclsyntax.TokenEqual,
@@ -356,9 +360,12 @@ func TestTokensForValue(t *testing.T) {
 					SpacesBefore: 1,
 				},
 				{
-					Type:         hclsyntax.TokenCBrace,
+					Type:  hclsyntax.TokenNewline,
-					Bytes:        []byte(`}`),
+					Bytes: []byte("\n"),
-					SpacesBefore: 1,
+				},
+				{
+					Type:  hclsyntax.TokenCBrace,
+					Bytes: []byte(`}`),
 				},
 			},
 		},
@@ -372,10 +379,14 @@ func TestTokensForValue(t *testing.T) {
 					Type:  hclsyntax.TokenOBrace,
 					Bytes: []byte(`{`),
 				},
+				{
+					Type:  hclsyntax.TokenNewline,
+					Bytes: []byte("\n"),
+				},
 				{
 					Type:         hclsyntax.TokenIdent,
 					Bytes:        []byte(`bar`),
-					SpacesBefore: 1,
+					SpacesBefore: 2,
 				},
 				{
 					Type:         hclsyntax.TokenEqual,
@@ -388,13 +399,13 @@ func TestTokensForValue(t *testing.T) {
 					SpacesBefore: 1,
 				},
 				{
-					Type:  hclsyntax.TokenComma,
+					Type:  hclsyntax.TokenNewline,
-					Bytes: []byte(`,`),
+					Bytes: []byte("\n"),
 				},
 				{
 					Type:         hclsyntax.TokenIdent,
 					Bytes:        []byte(`foo`),
-					SpacesBefore: 1,
+					SpacesBefore: 2,
 				},
 				{
 					Type:         hclsyntax.TokenEqual,
@@ -407,9 +418,12 @@ func TestTokensForValue(t *testing.T) {
 					SpacesBefore: 1,
 				},
 				{
-					Type:         hclsyntax.TokenCBrace,
+					Type:  hclsyntax.TokenNewline,
-					Bytes:        []byte(`}`),
+					Bytes: []byte("\n"),
-					SpacesBefore: 1,
+				},
+				{
+					Type:  hclsyntax.TokenCBrace,
+					Bytes: []byte(`}`),
 				},
 			},
 		},
@@ -422,10 +436,14 @@ func TestTokensForValue(t *testing.T) {
 					Type:  hclsyntax.TokenOBrace,
 					Bytes: []byte(`{`),
 				},
+				{
+					Type:  hclsyntax.TokenNewline,
+					Bytes: []byte("\n"),
+				},
 				{
 					Type:         hclsyntax.TokenOQuote,
 					Bytes:        []byte(`"`),
-					SpacesBefore: 1,
+					SpacesBefore: 2,
 				},
 				{
 					Type:  hclsyntax.TokenQuotedLit,
@@ -446,9 +464,12 @@ func TestTokensForValue(t *testing.T) {
 					SpacesBefore: 1,
 				},
 				{
-					Type:         hclsyntax.TokenCBrace,
+					Type:  hclsyntax.TokenNewline,
-					Bytes:        []byte(`}`),
+					Bytes: []byte("\n"),
-					SpacesBefore: 1,
+				},
+				{
+					Type:  hclsyntax.TokenCBrace,
+					Bytes: []byte(`}`),
 				},
 			},
 		},