From 99099cda627165f1e22d318c63978275d68e85c3 Mon Sep 17 00:00:00 2001
From: Fatih Arslan <ftharsln@gmail.com>
Date: Mon, 12 Oct 2015 01:38:59 +0300
Subject: [PATCH] parser: implement parsing assignments, stil wip

---
 parser/ast.go    | 32 +++++++++++++++++----
 parser/parser.go | 75 +++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 89 insertions(+), 18 deletions(-)

diff --git a/parser/ast.go b/parser/ast.go
index 76c5db3..70c7dc6 100644
--- a/parser/ast.go
+++ b/parser/ast.go
@@ -14,32 +14,54 @@ const (
 	Object
 )
 
-// Node is an element in the abstract syntax  tree.
+// Node is an element in the abstract syntax tree.
 type Node interface {
 	node()
 	String() string
 	Pos() scanner.Pos
 }
 
+func (Source) node()          {}
 func (IdentStatement) node()  {}
 func (BlockStatement) node()  {}
 func (AssignStatement) node() {}
 func (ListStatement) node()   {}
 func (ObjectStatement) node() {}
 
+// Source represents a single HCL source file
+type Source struct {
+	nodes []Node
+}
+
+func (s Source) add(node Node) {
+	s.nodes = append(s.nodes, node)
+}
+
+func (s Source) String() string {
+	buf := ""
+	for _, n := range s.nodes {
+		buf += n.String()
+	}
+
+	return buf
+}
+
+func (s Source) Pos() scanner.Pos {
+	// always returns the uninitiliazed position
+	return scanner.Pos{}
+}
+
 // IdentStatement represents an identifier.
 type IdentStatement struct {
-	pos   scanner.Pos // position of the literal
 	token scanner.Token
-	value string
 }
 
 func (i IdentStatement) String() string {
-	return i.value
+	return i.token.String()
 }
 
 func (i IdentStatement) Pos() scanner.Pos {
-	return i.pos
+	return i.token.Pos()
 }
 
 type BlockStatement struct {
diff --git a/parser/parser.go b/parser/parser.go
index a3513f6..695cee6 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -3,11 +3,12 @@ package parser
 import "github.com/fatih/hcl/scanner"
 
 type Parser struct {
-	sc  *scanner.Scanner
-	buf struct {
-		tok scanner.Token // last read token
-		n   int           // buffer size (max = 1)
-	}
+	sc *scanner.Scanner
+
+	tok     scanner.Token // last read token
+	prevTok scanner.Token // previous read token
+
+	n int // buffer size (max = 1)
 }
 
 func NewParser(src []byte) *Parser {
@@ -16,33 +17,81 @@ func NewParser(src []byte) *Parser {
 	}
 }
 
+// Parse returns the fully parsed source and returns the abstract syntax tree.
 func (p *Parser) Parse() Node {
 	tok := p.scan()
 
+	node := Source{}
+
 	switch tok.Type() {
 	case scanner.IDENT:
-		// p.parseStatement()
+		n := p.parseStatement()
+		node.add(n)
 	case scanner.EOF:
 	}
 
+	return node
+}
+
+func (p *Parser) parseStatement() Node {
+	tok := p.scan()
+
+	if tok.Type().IsLiteral() {
+		return p.parseIdent()
+	}
+
+	switch tok.Type() {
+	case scanner.LBRACE:
+		return p.parseObject()
+	case scanner.LBRACK:
+		return p.parseList()
+	case scanner.ASSIGN:
+		return p.parseAssignment()
+	}
 	return nil
 }
 
+func (p *Parser) parseIdent() Node {
+	return IdentStatement{
+		token: p.tok,
+	}
+}
+
+func (p *Parser) parseObject() Node {
+	return nil
+}
+
+func (p *Parser) parseList() Node {
+	return nil
+}
+
+func (p *Parser) parseAssignment() Node {
+	return AssignStatement{
+		lhs: IdentStatement{
+			token: p.prevTok,
+		},
+		assign: p.tok.Pos(),
+		rhs:    p.parseStatement(),
+	}
+}
+
 // scan returns the next token from the underlying scanner.
 // If a token has been unscanned then read that instead.
 func (p *Parser) scan() scanner.Token {
 	// If we have a token on the buffer, then return it.
-	if p.buf.n != 0 {
-		p.buf.n = 0
-		return p.buf.tok
+	if p.n != 0 {
+		p.n = 0
+		return p.tok
 	}
 
+	// store previous token
+	p.prevTok = p.tok
+
 	// Otherwise read the next token from the scanner and Save it to the buffer
 	// in case we unscan later.
-	p.buf.tok = p.sc.Scan()
-
-	return p.buf.tok
+	p.tok = p.sc.Scan()
+	return p.tok
 }
 
 // unscan pushes the previously read token back onto the buffer.
-func (p *Parser) unread() { p.buf.n = 1 }
+func (p *Parser) unscan() { p.n = 1 }