Ejemplo n.º 1
0
// setConst sets x to the untyped constant for literal lit.
func (x *operand) setConst(tok token.Token, lit string) {
	val := exact.MakeFromLiteral(lit, tok)
	if val == nil {
		// TODO(gri) Should we make it an unknown constant instead?
		x.mode = invalid
		return
	}

	var kind BasicKind
	switch tok {
	case token.INT:
		kind = UntypedInt
	case token.FLOAT:
		kind = UntypedFloat
	case token.IMAG:
		kind = UntypedComplex
	case token.CHAR:
		kind = UntypedRune
	case token.STRING:
		kind = UntypedString
	}

	x.mode = constant
	x.typ = Typ[kind]
	x.val = val
}
Ejemplo n.º 2
0
// number = int_lit [ "p" int_lit ] .
//
func (p *parser) parseNumber() (typ *types.Basic, val exact.Value) {
	// mantissa
	mant := exact.MakeFromLiteral(p.parseInt(), token.INT)
	if mant == nil {
		panic("invalid mantissa")
	}

	if p.lit == "p" {
		// exponent (base 2)
		p.next()
		exp, err := strconv.ParseInt(p.parseInt(), 10, 0)
		if err != nil {
			p.error(err)
		}
		if exp < 0 {
			denom := exact.MakeInt64(1)
			denom = exact.Shift(denom, token.SHL, uint(-exp))
			typ = types.Typ[types.UntypedFloat]
			val = exact.BinaryOp(mant, token.QUO, denom)
			return
		}
		if exp > 0 {
			mant = exact.Shift(mant, token.SHL, uint(exp))
		}
		typ = types.Typ[types.UntypedFloat]
		val = mant
		return
	}

	typ = types.Typ[types.UntypedInt]
	val = mant
	return
}
Ejemplo n.º 3
0
// matchExpr reports whether pattern x matches y.
//
// If tr.allowWildcards, Idents in x that refer to parameters are
// treated as wildcards, and match any y that is assignable to the
// parameter type; matchExpr records this correspondence in tr.env.
// Otherwise, matchExpr simply reports whether the two trees are
// equivalent.
//
// A wildcard appearing more than once in the pattern must
// consistently match the same tree.
//
func (tr *Transformer) matchExpr(x, y ast.Expr) bool {
	if x == nil && y == nil {
		return true
	}
	if x == nil || y == nil {
		return false
	}
	x = unparen(x)
	y = unparen(y)

	// Is x a wildcard?  (a reference to a 'before' parameter)
	if xobj, ok := tr.wildcardObj(x); ok {
		return tr.matchWildcard(xobj, y)
	}

	// Object identifiers (including pkg-qualified ones)
	// are handled semantically, not syntactically.
	xobj := isRef(x, tr.info)
	yobj := isRef(y, tr.info)
	if xobj != nil {
		return xobj == yobj
	}
	if yobj != nil {
		return false
	}

	// TODO(adonovan): audit: we cannot assume these ast.Exprs
	// contain non-nil pointers.  e.g. ImportSpec.Name may be a
	// nil *ast.Ident.

	if reflect.TypeOf(x) != reflect.TypeOf(y) {
		return false
	}
	switch x := x.(type) {
	case *ast.Ident:
		log.Fatalf("unexpected Ident: %s", astString(tr.fset, x))

	case *ast.BasicLit:
		y := y.(*ast.BasicLit)
		xval := exact.MakeFromLiteral(x.Value, x.Kind)
		yval := exact.MakeFromLiteral(y.Value, y.Kind)
		return exact.Compare(xval, token.EQL, yval)

	case *ast.FuncLit:
		// func literals (and thus statement syntax) never match.
		return false

	case *ast.CompositeLit:
		y := y.(*ast.CompositeLit)
		return (x.Type == nil) == (y.Type == nil) &&
			(x.Type == nil || tr.matchType(x.Type, y.Type)) &&
			tr.matchExprs(x.Elts, y.Elts)

	case *ast.SelectorExpr:
		y := y.(*ast.SelectorExpr)
		return tr.matchSelectorExpr(x, y) &&
			tr.info.Selections[x].Obj() == tr.info.Selections[y].Obj()

	case *ast.IndexExpr:
		y := y.(*ast.IndexExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Index, y.Index)

	case *ast.SliceExpr:
		y := y.(*ast.SliceExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Low, y.Low) &&
			tr.matchExpr(x.High, y.High) &&
			tr.matchExpr(x.Max, y.Max) &&
			x.Slice3 == y.Slice3

	case *ast.TypeAssertExpr:
		y := y.(*ast.TypeAssertExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchType(x.Type, y.Type)

	case *ast.CallExpr:
		y := y.(*ast.CallExpr)
		match := tr.matchExpr // function call
		if tr.info.Types[x.Fun].IsType() {
			match = tr.matchType // type conversion
		}
		return x.Ellipsis.IsValid() == y.Ellipsis.IsValid() &&
			match(x.Fun, y.Fun) &&
			tr.matchExprs(x.Args, y.Args)

	case *ast.StarExpr:
		y := y.(*ast.StarExpr)
		return tr.matchExpr(x.X, y.X)

	case *ast.UnaryExpr:
		y := y.(*ast.UnaryExpr)
		return x.Op == y.Op &&
			tr.matchExpr(x.X, y.X)

	case *ast.BinaryExpr:
		y := y.(*ast.BinaryExpr)
		return x.Op == y.Op &&
			tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Y, y.Y)

	case *ast.KeyValueExpr:
		y := y.(*ast.KeyValueExpr)
		return tr.matchExpr(x.Key, y.Key) &&
			tr.matchExpr(x.Value, y.Value)
	}

	panic(fmt.Sprintf("unhandled AST node type: %T", x))
}
Ejemplo n.º 4
0
// ConstValue     = string | "false" | "true" | ["-"] (int ["'"] | FloatOrComplex) .
// FloatOrComplex = float ["i" | ("+"|"-") float "i"] .
func (p *parser) parseConstValue() (val exact.Value, typ types.Type) {
	switch p.tok {
	case scanner.String:
		str := p.parseString()
		val = exact.MakeString(str)
		typ = types.Typ[types.UntypedString]
		return

	case scanner.Ident:
		b := false
		switch p.lit {
		case "false":
		case "true":
			b = true

		default:
			p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
		}

		p.next()
		val = exact.MakeBool(b)
		typ = types.Typ[types.UntypedBool]
		return
	}

	sign := ""
	if p.tok == '-' {
		p.next()
		sign = "-"
	}

	switch p.tok {
	case scanner.Int:
		val = exact.MakeFromLiteral(sign+p.lit, token.INT)
		if val == nil {
			p.error("could not parse integer literal")
		}

		p.next()
		if p.tok == '\'' {
			p.next()
			typ = types.Typ[types.UntypedRune]
		} else {
			typ = types.Typ[types.UntypedInt]
		}

	case scanner.Float:
		re := sign + p.lit
		p.next()

		var im string
		switch p.tok {
		case '+':
			p.next()
			im = p.expect(scanner.Float)

		case '-':
			p.next()
			im = "-" + p.expect(scanner.Float)

		case scanner.Ident:
			// re is in fact the imaginary component. Expect "i" below.
			im = re
			re = "0"

		default:
			val = exact.MakeFromLiteral(re, token.FLOAT)
			if val == nil {
				p.error("could not parse float literal")
			}
			typ = types.Typ[types.UntypedFloat]
			return
		}

		p.expectKeyword("i")
		reval := exact.MakeFromLiteral(re, token.FLOAT)
		if reval == nil {
			p.error("could not parse real component of complex literal")
		}
		imval := exact.MakeFromLiteral(im+"i", token.IMAG)
		if imval == nil {
			p.error("could not parse imag component of complex literal")
		}
		val = exact.BinaryOp(reval, token.ADD, imval)
		typ = types.Typ[types.UntypedComplex]

	default:
		p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
	}

	return
}
Ejemplo n.º 5
0
// ConstDecl   = "const" ExportedName [ Type ] "=" Literal .
// Literal     = bool_lit | int_lit | float_lit | complex_lit | rune_lit | string_lit .
// bool_lit    = "true" | "false" .
// complex_lit = "(" float_lit "+" float_lit "i" ")" .
// rune_lit    = "(" int_lit "+" int_lit ")" .
// string_lit  = `"` { unicode_char } `"` .
//
func (p *parser) parseConstDecl() {
	p.expectKeyword("const")
	pkg, name := p.parseExportedName()

	var typ0 types.Type
	if p.tok != '=' {
		typ0 = p.parseType()
	}

	p.expect('=')
	var typ types.Type
	var val exact.Value
	switch p.tok {
	case scanner.Ident:
		// bool_lit
		if p.lit != "true" && p.lit != "false" {
			p.error("expected true or false")
		}
		typ = types.Typ[types.UntypedBool]
		val = exact.MakeBool(p.lit == "true")
		p.next()

	case '-', scanner.Int:
		// int_lit
		typ, val = p.parseNumber()

	case '(':
		// complex_lit or rune_lit
		p.next()
		if p.tok == scanner.Char {
			p.next()
			p.expect('+')
			typ = types.Typ[types.UntypedRune]
			_, val = p.parseNumber()
			p.expect(')')
			break
		}
		_, re := p.parseNumber()
		p.expect('+')
		_, im := p.parseNumber()
		p.expectKeyword("i")
		p.expect(')')
		typ = types.Typ[types.UntypedComplex]
		val = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))

	case scanner.Char:
		// rune_lit
		typ = types.Typ[types.UntypedRune]
		val = exact.MakeFromLiteral(p.lit, token.CHAR)
		p.next()

	case scanner.String:
		// string_lit
		typ = types.Typ[types.UntypedString]
		val = exact.MakeFromLiteral(p.lit, token.STRING)
		p.next()

	default:
		p.errorf("expected literal got %s", scanner.TokenString(p.tok))
	}

	if typ0 == nil {
		typ0 = typ
	}

	pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, typ0, val))
}