From e7ae30194771059523eb13638b72ce955364d16a Mon Sep 17 00:00:00 2001
From: gedi <gediminas.morkevicius@gmail.com>
Date: Sun, 7 Jun 2015 11:18:46 +0300
Subject: [PATCH] begin with parser implementation

---
 gherkin/lexer/lexer.go | 13 +++++--
 gherkin/parse.go       | 86 ++++++++++++++++++++++++++++++++++++------
 2 files changed, 84 insertions(+), 15 deletions(-)

diff --git a/gherkin/lexer/lexer.go b/gherkin/lexer/lexer.go
index 48c6e17..88a8260 100644
--- a/gherkin/lexer/lexer.go
+++ b/gherkin/lexer/lexer.go
@@ -19,13 +19,20 @@ func New(r io.Reader) *Lexer {
 	}
 }
 
-func (l *Lexer) Next() (t *Token) {
+func (l *Lexer) Next(skip ...TokenType) (t *Token) {
 	if l.peek != nil {
 		t = l.peek
 		l.peek = nil
-		return
+	} else {
+		t = l.read()
 	}
-	return l.read()
+
+	for _, typ := range skip {
+		if t.Type == typ {
+			return l.Next(skip...)
+		}
+	}
+	return
 }
 
 func (l *Lexer) Peek() *Token {
diff --git a/gherkin/parse.go b/gherkin/parse.go
index 5cb41e3..b189a49 100644
--- a/gherkin/parse.go
+++ b/gherkin/parse.go
@@ -1,16 +1,22 @@
 package gherkin
 
+import (
+	"errors"
+	"io"
+	"strings"
+
+	"github.com/l3pp4rd/behat/gherkin/lexer"
+)
+
 type Tag string
 
 type Scenario struct {
 	Steps []*Step
 	Tags  []Tag
-	Line  string
 }
 
 type Background struct {
 	Steps []*Step
-	Line  string
 }
 
 type StepType string
@@ -22,7 +28,6 @@ const (
 )
 
 type Step struct {
-	Line string
 	Text string
 	Type StepType
 }
@@ -30,17 +35,74 @@ type Step struct {
 type Feature struct {
 	Tags        []Tag
 	Description string
-	Line        string
 	Title       string
-	Filename    string
 	Background  *Background
 	Scenarios   []*Scenario
 }
 
-// func Parse(r io.Reader) (*Feature, error) {
-// 	in := bufio.NewReader(r)
-// 	for line, err := in.ReadString(byte('\n')); err != nil; line, err = in.ReadString(byte('\n')) {
-// 		ln := strings.TrimFunc(string(line), unicode.IsSpace)
-// 	}
-// 	return nil, nil
-// }
+var ErrNotFeature = errors.New("expected a file to begin with a feature definition")
+var ErrEmpty = errors.New("the feature file is empty")
+var ErrTagsNextToFeature = errors.New("tags must be a single line next to a feature definition")
+var ErrSingleBackground = errors.New("there can only be a single background section")
+
+type parser struct {
+	lx *lexer.Lexer
+}
+
+func Parse(r io.Reader) (*Feature, error) {
+	return (parser{lx: lexer.New(r)}).parseFeature()
+}
+
+func (p parser) parseFeature() (*Feature, error) {
+	var tok *lexer.Token = p.lx.Next(lexer.COMMENT, lexer.NEW_LINE)
+	if tok.Type == lexer.EOF {
+		return nil, ErrEmpty
+	}
+
+	ft := &Feature{}
+	if tok.Type == lexer.TAGS {
+		if p.lx.Peek().Type != lexer.FEATURE {
+			return ft, ErrTagsNextToFeature
+		}
+		ft.Tags = p.parseTags(tok.Value)
+		tok = p.lx.Next()
+	}
+
+	if tok.Type != lexer.FEATURE {
+		return ft, ErrNotFeature
+	}
+
+	ft.Title = tok.Value
+	var desc []string
+	for ; p.lx.Peek().Type == lexer.TEXT; tok = p.lx.Next() {
+		desc = append(desc, tok.Value)
+	}
+	ft.Description = strings.Join(desc, "\n")
+
+	tok = p.lx.Next(lexer.COMMENT, lexer.NEW_LINE)
+	for ; tok.Type != lexer.EOF; p.lx.Next(lexer.COMMENT, lexer.NEW_LINE) {
+		if tok.Type == lexer.BACKGROUND {
+			if ft.Background != nil {
+				return ft, ErrSingleBackground
+			}
+			ft.Background = p.parseBackground()
+			continue
+		}
+	}
+
+	return ft, nil
+}
+
+func (p parser) parseBackground() *Background {
+	return nil
+}
+
+func (p parser) parseTags(s string) (tags []Tag) {
+	for _, tag := range strings.Split(s, " ") {
+		t := strings.Trim(tag, "@ ")
+		if len(t) > 0 {
+			tags = append(tags, Tag(t))
+		}
+	}
+	return
+}