WIP on v1

parser.go

@@ -2,66 +2,107 @@ package conf
 
 import (
 	"bufio"
+	"errors"
+	"fmt"
 	"io"
 	"os"
-	"regexp"
 	"strings"
 )
 
-var (
-	configKeyValueRe   = regexp.MustCompile(`(\w+) *= *(.+)\b[\t| |\n]*`)
-	configOptionRe     = regexp.MustCompile(`(\w+)`)
-	configCommentedOut = "#"
+const (
+	strComment = "#"
+	strEqSign  = "="
 )
 
-// ParseFile reads values from file. It returns nil and error if os.Open(filename) fails.
+var (
+	ErrFormat       = errors.New("conf: line does not match \"key = value\" pattern")
+	ErrDuplicateKey = errors.New("conf: duplicate key found")
+)
+
+// Open reads values from file. It returns nil and error if os.Open(filename) fails.
 // It would be wise to always check returned error.
 // ParseFile captures two types of values: "key = value" and "option". Either key value pair or
 // option must be put in its own line in the file.
 // Key or option must be a single word. In example line:
-// 	"option1 option2"
+//
+//	"option1 option2"
+//
 // only option1 will be captured. option2 needs to be in a separate line in the file to take effect.
 // In line "key = value1,value2,value3" all of value1, value2, and value3 will be
 // captured. They can be later accesed separately with Setting's Split() method.
-func ParseFile(filename string) (*Config, error) {
+func Open(filename string) (*Conf, error) {
 	file, err := os.Open(filename)
 	if err != nil {
 		return nil, err
 	}
-	defer file.Close()
-	return parseReader(file), nil
+
+	c, err := parseReader(file)
+	if err != nil {
+		return nil, err
+	}
+
+	return c, file.Close()
 }
 
-// ParseReader reads from r and returns Config. See also ParseFile.
-func ParseReader(r io.Reader) *Config {
+// Read reads from r and returns Config.
+func Read(r io.Reader) (*Conf, error) {
 	return parseReader(r)
 }
 
-// ParseReadCloser reads from r, returns Config and calls r.Close().
-// See also ParseFile.
-func ParseReadCloser(r io.ReadCloser) *Config {
-	defer r.Close()
-	return parseReader(r)
-}
+func parseReader(r io.Reader) (*Conf, error) {
+	settings := make(map[string]string)
 
-func parseReader(r io.Reader) *Config {
-	var c Config
-	c.Settings = make(map[string]string)
-	c.Options = make(map[string]struct{})
 	scanner := bufio.NewScanner(r)
+
 	for scanner.Scan() {
 		line := scanner.Text()
-		if strings.HasPrefix(line, configCommentedOut) {
+
+		line = trim(stripComment(line))
+		if line == "" {
 			continue
 		}
-		switch {
-		case configKeyValueRe.MatchString(line):
-			kvpair := configKeyValueRe.FindStringSubmatch(line)
-			c.Settings[kvpair[1]] = kvpair[2]
-		case configOptionRe.MatchString(line):
-			opt := configOptionRe.FindString(line)
-			c.Options[opt] = struct{}{}
+
+		key, value, ok := toKV(line)
+		if !ok {
+			return nil, ErrFormat
 		}
+
+		if _, ok := settings[key]; ok {
+			return nil, fmt.Errorf("%w: %s", ErrDuplicateKey, key)
+		}
+
+		settings[key] = value
 	}
-	return &c
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return &Conf{
+		settings: settings,
+	}, nil
+}
+
+func toKV(s string) (string, string, bool) {
+	k, v, ok := strings.Cut(s, strEqSign)
+	if !ok || k == "" || v == "" {
+		return "", "", false
+	}
+
+	return trim(k), trim(v), true
+}
+
+func trim(s string) string {
+	s = strings.TrimSpace(s)
+
+	return s
+}
+
+func stripComment(s string) string {
+	idx := strings.Index(s, strComment)
+	if idx > -1 {
+		s = s[:idx]
+	}
+
+	return s
 }