parser: add initial AST definitions

parser/ast.go

@@ -0,0 +1,56 @@
+package parser
+
+import "github.com/fatih/hcl/scanner"
+
+type NodeType int
+
+const (
+	Unknown NodeType = 0
+	Number
+	Float
+	Bool
+	String
+	List
+	Object
+)
+
+// Node is an element in the parse tree.
+type Node interface {
+	String() string
+	Type() NodeType
+	Start() scanner.Pos
+	End() scanner.Pos
+}
+
+// IdentStatement represents an identifier.
+type IdentStatement struct {
+	Token scanner.Token
+	Pos   scanner.Pos // position of the literal
+	Value string
+}
+
+type BlockStatement struct {
+	Lbrace scanner.Pos // position of "{"
+	Rbrace scanner.Pos // position of "}"
+	List   []Node      // the nodes in lexical order
+}
+
+// AssignStatement represents an assignment
+type AssignStatement struct {
+	Lhs    Node        // left hand side of the assignment
+	Rhs    Node        // right hand side of the assignment
+	Assign scanner.Pos // position of "="
+}
+
+// ListStatement represents a list
+type ListStatement struct {
+	Lbrack scanner.Pos // position of "["
+	Rbrack scanner.Pos // position of "]"
+	List   []Node      // the elements in lexical order
+}
+
+// ObjectStatment represents an object
+type ObjectStatement struct {
+	Idents []Node // the idents in elements in lexical order
+	BlockStatement
+}

parser/parser.go

@@ -1 +1,16 @@
 package parser
+
+import "github.com/fatih/hcl/scanner"
+
+type Parser struct {
+	sc *scanner.Scanner
+}
+
+func NewParser(src []byte) *Parser {
+	return &Parser{
+		sc: scanner.NewScanner(src),
+	}
+}
+
+func (p *Parser) Parse() {
+}

scanner/position.go

@@ -2,10 +2,10 @@ package scanner
 
 import "fmt"
 
-// Position describes an arbitrary source position
+// Pos describes an arbitrary source position
 // including the file, line, and column location.
 // A Position is valid if the line number is > 0.
-type Position struct {
+type Pos struct {
 	Filename string // filename, if any
 	Offset   int    // offset, starting at 0
 	Line     int    // line number, starting at 1
@@ -13,7 +13,7 @@ type Position struct {
 }
 
 // IsValid returns true if the position is valid.
-func (p *Position) IsValid() bool { return p.Line > 0 }
+func (p *Pos) IsValid() bool { return p.Line > 0 }
 
 // String returns a string in one of several forms:
 //
@@ -21,7 +21,7 @@ func (p *Position) IsValid() bool { return p.Line > 0 }
 //	line:column         valid position without file name
 //	file                invalid position with file name
 //	-                   invalid position without file name
-func (p Position) String() string {
+func (p Pos) String() string {
 	s := p.Filename
 	if p.IsValid() {
 		if s != "" {

scanner/scanner.go

@@ -19,8 +19,8 @@ type Scanner struct {
 	src []byte        // Source buffer for immutable access
 
 	// Source Position
-	srcPos  Position // current position
+	srcPos  Pos // current position
-	prevPos Position // previous position, used for peek() method
+	prevPos Pos // previous position, used for peek() method
 
 	lastCharLen int // length of last character in bytes
 	lastLineLen int // length of last line in characters (for correct column reporting)
@@ -30,7 +30,7 @@ type Scanner struct {
 
 	// Error is called for each error encountered. If no Error
 	// function is set, the error is reported to os.Stderr.
-	Error func(pos Position, msg string)
+	Error func(pos Pos, msg string)
 
 	// ErrorCount is incremented by one for each error encountered.
 	ErrorCount int
@@ -39,7 +39,7 @@ type Scanner struct {
 	// Scan. The Filename field is always left untouched by the Scanner.  If
 	// an error is reported (via Error) and Position is invalid, the scanner is
 	// not inside a token.
-	tokPos Position
+	tokPos Pos
 }
 
 // NewScannerstring creates and initializes a new instance of Scanner using
@@ -449,7 +449,7 @@ func (s *Scanner) scanIdentifier() string {
 
 // recentPosition returns the position of the character immediately after the
 // character or token returned by the last call to Scan.
-func (s *Scanner) recentPosition() (pos Position) {
+func (s *Scanner) recentPosition() (pos Pos) {
 	pos.Offset = s.srcPos.Offset - s.lastCharLen
 	switch {
 	case s.srcPos.Column > 0:

scanner/scanner_test.go

@@ -184,7 +184,7 @@ func TestPosition(t *testing.T) {
 
 	s := NewScanner(buf.Bytes())
 
-	pos := Position{"", 4, 1, 5}
+	pos := Pos{"", 4, 1, 5}
 	s.Scan()
 	for _, listName := range orderedTokenLists {
 
@@ -369,7 +369,7 @@ func testError(t *testing.T, src, pos, msg string, tok TokenType) {
 	s := NewScanner([]byte(src))
 
 	errorCalled := false
-	s.Error = func(p Position, m string) {
+	s.Error = func(p Pos, m string) {
 		if !errorCalled {
 			if pos != p.String() {
 				t.Errorf("pos = %q, want %q for %q", p, pos, src)

scanner/token.go

@@ -5,7 +5,7 @@ import "strconv"
 // Token defines a single HCL token which can be obtained via the Scanner
 type Token struct {
 	token TokenType
-	pos   Position
+	pos   Pos
 	text  string
 }
 
@@ -92,7 +92,7 @@ func (t Token) Type() TokenType {
 }
 
 // Pos returns the token's position
-func (t Token) Pos() Position {
+func (t Token) Pos() Pos {
 	return t.pos
 }