Fix formatting of multiline strings

Author: breml

ast/ast_helper.go

@@ -3,9 +3,17 @@ package ast
 import (
 	"bytes"
 	"fmt"
+	"regexp"
 	"strings"
 )
 
+// This regular expression splits the config into indentable chunks that are:
+// * empty line
+// * line of comment
+// * line without any quotes
+// * line(s) with quoted strings, which are kept together to form a single "line of configuration"
+var linesRe = regexp.MustCompile(`(\n|\s*//[^\n]*\n|[^'"\n]*\n|([^"'\n]*("(\\"|[^"])*"|'(\\'|[^'])*')[^"'\n]*)*\n)`)
+
 func prefix(in string, emptyNewline bool) string {
 	if len(in) == 0 {
 		if emptyNewline {
@@ -16,13 +24,13 @@ func prefix(in string, emptyNewline bool) string {
 
 	var s bytes.Buffer
 	s.WriteString("\n")
-	lines := strings.Split(strings.TrimRight(in, "\n"), "\n")
+	lines := linesRe.FindAllString(strings.TrimRight(in, "\n")+"\n", -1)
 	for _, l := range lines {
-		if len(l) == 0 {
+		if len(strings.TrimLeft(l, " \n")) == 0 {
 			s.WriteString("\n")
 			continue
 		}
-		s.WriteString(fmt.Sprintln("  " + l))
+		s.WriteString(fmt.Sprint("  " + l))
 	}
 	return s.String()
 }

ast/ast_helper_test.go

@@ -20,15 +20,7 @@ func TestPrefix(t *testing.T) {
 			want: "\n",
 		},
 		{
-			name:  "simple attribute",
-			input: `value => 3.1415`,
-
-			want: `
-  value => 3.1415
-`,
-		},
-		{
-			name: "simple attribute with newline",
+			name: "simple attribute",
 			input: `value => 3.1415
 `,
 
@@ -39,7 +31,8 @@ func TestPrefix(t *testing.T) {
 		{
 			name: "simple attribute with comment",
 			input: `// comment
-value => 3.1415`,
+value => 3.1415
+`,
 
 			want: `
   // comment
@@ -63,6 +56,56 @@ add_tag => [ "foobar" ]
   }
 
   add_tag => [ "foobar" ]
+`,
+		},
+		{
+			name: "attribute with multiline string attribute",
+			input: `value => "string
+with multiple
+lines"
+othervalue => 3.1415
+`,
+
+			want: `
+  value => "string
+with multiple
+lines"
+  othervalue => 3.1415
+`,
+		},
+		{
+			name: "attribute with multiline string attribute (single quote)",
+			input: `value => 'string
+with multiple
+lines'
+othervalue => 3.1415
+`,
+
+			want: `
+  value => 'string
+with multiple
+lines'
+  othervalue => 3.1415
+`,
+		},
+		{
+			name: "comment with double and single quote",
+			input: `// comment with " and '
+othervalue => 3.1415
+`,
+
+			want: `
+  // comment with " and '
+  othervalue => 3.1415
+`,
+		},
+		{
+			name: "array with multiple string types",
+			input: `value => [ "string", 'string', string ]
+`,
+
+			want: `
+  value => [ "string", 'string', string ]
 `,
 		},
 	}

logstash_config_test.go

@@ -368,6 +368,19 @@ output {}
     }
   }
 }
+`,
+		},
+		{
+			name: "multiline string",
+			input: `filter {
+  mutate {
+    add_field => {
+      "largeint" => "a string
+with multiple
+lines"
+    }
+  }
+}
 `,
 		},
 	}