parse: fix format for multi error report (#24)

Author: a8m

cmd/envsubst/main.go

@@ -34,7 +34,6 @@ func main() {
 		fmt.Fprint(os.Stderr, fmt.Sprintf(usage))
 	}
 	flag.Parse()
-	// Reader
 	var reader *bufio.Reader
 	if *input != "" {
 		file, err := os.Open(*input)
@@ -50,7 +49,7 @@ func main() {
 		}
 		reader = bufio.NewReader(os.Stdin)
 	}
-	// Collect data
+	// Collect input data.
 	var data string
 	for {
 		line, err := reader.ReadString('\n')
@@ -63,9 +62,10 @@ func main() {
 		}
 		data += line
 	}
-	// Writer
-	var file *os.File
-	var err error
+	var (
+		err  error
+		file *os.File
+	)
 	if *output != "" {
 		file, err = os.Create(*output)
 		if err != nil {
@@ -80,9 +80,7 @@ func main() {
 		parserMode = parse.Quick
 	}
 	restrictions := &parse.Restrictions{*noUnset, *noEmpty}
-
-	result, err := (*&parse.Parser{Name: "string", Env: os.Environ(), Restrict: restrictions, Mode: parserMode}).Parse(data)
-
+	result, err := (&parse.Parser{Name: "string", Env: os.Environ(), Restrict: restrictions, Mode: parserMode}).Parse(data)
 	if err != nil {
 		errorAndExit(err)
 	}

parse/parse.go

@@ -3,23 +3,24 @@ package parse
 
 import (
 	"errors"
-	"fmt"
 	"strings"
 )
 
+// A mode value is a set of flags (or 0). They control parser behavior.
 type Mode int
 
-type Restrictions struct {
-	NoUnset bool
-	NoEmpty bool
-}
-
 // Mode for parser behaviour
 const (
 	Quick     Mode = iota // stop parsing after first error encoutered and return
 	AllErrors             // report all errors
 )
 
+// The restrictions option controls the parsring restriction.
+type Restrictions struct {
+	NoUnset bool
+	NoEmpty bool
+}
+
 // Restrictions specifier
 var (
 	Relaxed = &Restrictions{false, false}
@@ -54,33 +55,40 @@ func New(name string, env []string, r *Restrictions) *Parser {
 func (p *Parser) Parse(text string) (string, error) {
 	p.lex = lex(text)
 	// Build internal array of all unset or empty vars here
-	var allErrors string
+	var errs []error
 	// clean parse state
 	p.nodes = make([]Node, 0)
 	p.peekCount = 0
 	if err := p.parse(); err != nil {
-		switch *&p.Mode {
+		switch p.Mode {
 		case Quick:
 			return "", err
 		case AllErrors:
-			allErrors += fmt.Sprintf("%s\n", err.Error())
+			errs = append(errs, err)
 		}
 	}
 	var out string
 	for _, node := range p.nodes {
 		s, err := node.String()
 		if err != nil {
-			switch *&p.Mode {
+			switch p.Mode {
 			case Quick:
 				return "", err
 			case AllErrors:
-				allErrors += fmt.Sprintf("%s\n", err.Error())
+				errs = append(errs, err)
 			}
 		}
 		out += s
 	}
-	if allErrors != "" {
-		return "", fmt.Errorf("%s", allErrors)
+	if len(errs) > 0 {
+		var b strings.Builder
+		for i, err := range errs {
+			if i > 0 {
+				b.WriteByte('\n')
+			}
+			b.WriteString(err.Error())
+		}
+		return "", errors.New(b.String())
 	}
 	return out, nil
 }

parse/parse_test.go

@@ -109,7 +109,7 @@ var parseTests = []parseTest{
 }
 
 var negativeParseTests = []parseTest{
-	{"$NOTSET and EMPTY are displayed as in full error output", "${NOTSET} and $EMPTY", "variable ${NOTSET} not set\nvariable ${EMPTY} set but empty\n", errAllFull},
+	{"$NOTSET and EMPTY are displayed as in full error output", "${NOTSET} and $EMPTY", "variable ${NOTSET} not set\nvariable ${EMPTY} set but empty", errAllFull},
 }
 
 func TestParse(t *testing.T) {