pkg/compiler: support negative integers

Currently we have to use 0xffffffffffffffff to represent -1,
and we can't express e.g. -20:20 int range.
Support negative consts to fix both problems.

6 files changed, 55 insertions, 47 deletions

diff --git a/pkg/ast/ast.go b/pkg/ast/ast.go
index 610d22f30..1e1e97221 100644
--- a/pkg/ast/ast.go
+++ b/pkg/ast/ast.go
@@ -169,19 +169,20 @@ func (n *String) Info() (Pos, string, string) {
 	return n.Pos, tok2str[tokString], ""
 }
 
-type intFmt int
+type IntFmt int
 
 const (
-	intFmtDec intFmt = iota
-	intFmtHex
-	intFmtChar
+	IntFmtDec IntFmt = iota
+	IntFmtNeg
+	IntFmtHex
+	IntFmtChar
 )
 
 type Int struct {
 	Pos Pos
 	// Only one of Value, Ident, CExpr is filled.
 	Value    uint64
-	valueFmt intFmt
+	ValueFmt IntFmt
 	Ident    string
 	CExpr    string
 }
@@ -194,7 +195,7 @@ type Type struct {
 	Pos Pos
 	// Only one of Value, Ident, String is filled.
 	Value     uint64
-	valueFmt  intFmt
+	ValueFmt  IntFmt
 	Ident     string
 	String    string
 	HasString bool
@@ -202,7 +203,7 @@ type Type struct {
 	HasColon  bool
 	Pos2      Pos
 	Value2    uint64
-	value2Fmt intFmt
+	Value2Fmt IntFmt
 	Ident2    string
 	Args      []*Type
 }
diff --git a/pkg/ast/clone.go b/pkg/ast/clone.go
index 9ccc3ea76..072425115 100644
--- a/pkg/ast/clone.go
+++ b/pkg/ast/clone.go
@@ -165,7 +165,7 @@ func (n *Int) Clone() Node {
 	return &Int{
 		Pos:      n.Pos,
 		Value:    n.Value,
-		valueFmt: n.valueFmt,
+		ValueFmt: n.ValueFmt,
 		Ident:    n.Ident,
 		CExpr:    n.CExpr,
 	}
@@ -179,14 +179,14 @@ func (n *Type) Clone() Node {
 	return &Type{
 		Pos:       n.Pos,
 		Value:     n.Value,
-		valueFmt:  n.valueFmt,
+		ValueFmt:  n.ValueFmt,
 		Ident:     n.Ident,
 		String:    n.String,
 		HasString: n.HasString,
 		HasColon:  n.HasColon,
 		Pos2:      n.Pos2,
 		Value2:    n.Value2,
-		value2Fmt: n.value2Fmt,
+		Value2Fmt: n.Value2Fmt,
 		Ident2:    n.Ident2,
 		Args:      args,
 	}
diff --git a/pkg/ast/format.go b/pkg/ast/format.go
index 5022d5da1..13cd26e2c 100644
--- a/pkg/ast/format.go
+++ b/pkg/ast/format.go
@@ -35,6 +35,21 @@ func SerializeNode(n Node) string {
 	return buf.String()
 }
 
+func FormatInt(v uint64, format IntFmt) string {
+	switch format {
+	case IntFmtDec:
+		return fmt.Sprint(v)
+	case IntFmtNeg:
+		return fmt.Sprint(int64(v))
+	case IntFmtHex:
+		return fmt.Sprintf("0x%x", v)
+	case IntFmtChar:
+		return fmt.Sprintf("'%c'", v)
+	default:
+		panic(fmt.Sprintf("unknown int format %v", format))
+	}
+}
+
 type serializer interface {
 	serialize(w io.Writer)
 }
@@ -159,14 +174,14 @@ func fmtType(t *Type) string {
 	case t.HasString:
 		v = fmt.Sprintf("\"%v\"", t.String)
 	default:
-		v = fmtIntValue(t.Value, t.valueFmt)
+		v = FormatInt(t.Value, t.ValueFmt)
 	}
 	if t.HasColon {
 		switch {
 		case t.Ident2 != "":
 			v += fmt.Sprintf(":%v", t.Ident2)
 		default:
-			v += fmt.Sprintf(":%v", fmtIntValue(t.Value2, t.value2Fmt))
+			v += fmt.Sprintf(":%v", FormatInt(t.Value2, t.Value2Fmt))
 		}
 	}
 	v += fmtTypeList(t.Args)
@@ -206,20 +221,7 @@ func fmtInt(i *Int) string {
 	case i.CExpr != "":
 		return fmt.Sprintf("%v", i.CExpr)
 	default:
-		return fmtIntValue(i.Value, i.valueFmt)
-	}
-}
-
-func fmtIntValue(v uint64, format intFmt) string {
-	switch format {
-	case intFmtDec:
-		return fmt.Sprint(v)
-	case intFmtHex:
-		return fmt.Sprintf("0x%x", v)
-	case intFmtChar:
-		return fmt.Sprintf("'%c'", v)
-	default:
-		panic(fmt.Sprintf("unknown int format %v", format))
+		return FormatInt(i.Value, i.ValueFmt)
 	}
 }
 
diff --git a/pkg/ast/parser.go b/pkg/ast/parser.go
index e4c5d8742..d43011796 100644
--- a/pkg/ast/parser.go
+++ b/pkg/ast/parser.go
@@ -413,7 +413,7 @@ func (p *parser) parseType() *Type {
 	switch p.tok {
 	case tokInt:
 		allowColon = true
-		arg.Value, arg.valueFmt = p.parseIntValue()
+		arg.Value, arg.ValueFmt = p.parseIntValue()
 	case tokIdent:
 		allowColon = true
 		arg.Ident = p.lit
@@ -429,7 +429,7 @@ func (p *parser) parseType() *Type {
 		arg.Pos2 = p.pos
 		switch p.tok {
 		case tokInt:
-			arg.Value2, arg.value2Fmt = p.parseIntValue()
+			arg.Value2, arg.Value2Fmt = p.parseIntValue()
 		case tokIdent:
 			arg.Ident2 = p.lit
 		default:
@@ -479,7 +479,7 @@ func (p *parser) parseInt() *Int {
 	}
 	switch p.tok {
 	case tokInt:
-		i.Value, i.valueFmt = p.parseIntValue()
+		i.Value, i.ValueFmt = p.parseIntValue()
 	case tokIdent:
 		i.Ident = p.lit
 	default:
@@ -489,16 +489,19 @@ func (p *parser) parseInt() *Int {
 	return i
 }
 
-func (p *parser) parseIntValue() (uint64, intFmt) {
+func (p *parser) parseIntValue() (uint64, IntFmt) {
 	if p.lit[0] == '\'' {
-		return uint64(p.lit[1]), intFmtChar
+		return uint64(p.lit[1]), IntFmtChar
 	}
 	if v, err := strconv.ParseUint(p.lit, 10, 64); err == nil {
-		return v, intFmtDec
+		return v, IntFmtDec
+	}
+	if v, err := strconv.ParseInt(p.lit, 10, 64); err == nil {
+		return uint64(v), IntFmtNeg
 	}
 	if len(p.lit) > 2 && p.lit[0] == '0' && p.lit[1] == 'x' {
 		if v, err := strconv.ParseUint(p.lit[2:], 16, 64); err == nil {
-			return v, intFmtHex
+			return v, IntFmtHex
 		}
 	}
 	panic(fmt.Sprintf("scanner returned bad integer %q", p.lit))
diff --git a/pkg/ast/scanner.go b/pkg/ast/scanner.go
index 67e7f50bd..af9ac562f 100644
--- a/pkg/ast/scanner.go
+++ b/pkg/ast/scanner.go
@@ -150,7 +150,7 @@ func (s *scanner) Scan() (tok token, lit string, pos Pos) {
 	case s.ch == '"' || s.ch == '<':
 		tok = tokString
 		lit = s.scanStr(pos)
-	case s.ch >= '0' && s.ch <= '9':
+	case s.ch >= '0' && s.ch <= '9' || s.ch == '-':
 		tok = tokInt
 		lit = s.scanInt(pos)
 	case s.ch == '\'':
@@ -211,25 +211,26 @@ func (s *scanner) scanStr(pos Pos) string {
 func (s *scanner) scanInt(pos Pos) string {
 	for s.ch >= '0' && s.ch <= '9' ||
 		s.ch >= 'a' && s.ch <= 'f' ||
-		s.ch >= 'A' && s.ch <= 'F' || s.ch == 'x' {
+		s.ch >= 'A' && s.ch <= 'F' ||
+		s.ch == 'x' || s.ch == '-' {
 		s.next()
 	}
 	lit := string(s.data[pos.Off:s.off])
-	bad := false
-	if _, err := strconv.ParseUint(lit, 10, 64); err != nil {
-		if len(lit) > 2 && lit[0] == '0' && lit[1] == 'x' {
-			if _, err := strconv.ParseUint(lit[2:], 16, 64); err != nil {
-				bad = true
-			}
-		} else {
-			bad = true
+	if _, err := strconv.ParseUint(lit, 10, 64); err == nil {
+		return lit
+	}
+	if len(lit) > 1 && lit[0] == '-' {
+		if _, err := strconv.ParseInt(lit, 10, 64); err == nil {
+			return lit
 		}
 	}
-	if bad {
-		s.Error(pos, fmt.Sprintf("bad integer %q", lit))
-		lit = "0"
+	if len(lit) > 2 && lit[0] == '0' && lit[1] == 'x' {
+		if _, err := strconv.ParseUint(lit[2:], 16, 64); err == nil {
+			return lit
+		}
 	}
-	return lit
+	s.Error(pos, fmt.Sprintf("bad integer %q", lit))
+	return "0"
 }
 
 func (s *scanner) scanChar(pos Pos) string {
diff --git a/pkg/ast/testdata/all.txt b/pkg/ast/testdata/all.txt
index 6c818eca6..6e4e72d2c 100644
--- a/pkg/ast/testdata/all.txt
+++ b/pkg/ast/testdata/all.txt
@@ -12,6 +12,7 @@ int_flags = 0, "foo"			### unexpected string, expecting int, identifier
 int_flags2 = '				### char literal is not terminated
 int_flags3 = 'a				### char literal is not terminated
 int_flags3 = 'a, 1			### char literal is not terminated
+int_flags4 = 1, -2-			### bad integer "-2-"
 
 str_flags0 = "foo", "bar"
 str_flags1 = "non terminated		### string literal is not terminated