cmd/compile/internal/syntax: fix lexing of ".45e1" and add token tests

2 files changed, 217 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/syntax/scanner.go b/src/cmd/compile/internal/syntax/scanner.go
index ac6baf7e58..9ad165f820 100644
--- a/src/cmd/compile/internal/syntax/scanner.go
+++ b/src/cmd/compile/internal/syntax/scanner.go
@@ -20,8 +20,8 @@ type scanner struct {
 	pos, line int
 	tok       token
 	lit       string   // valid if tok is _Name or _Literal
-	op        Operator // valid if tok is _Operator
-	prec      int      // valid if tok is _Operator
+	op        Operator // valid if tok is _Operator, _AssignOp, or _IncOp
+	prec      int      // valid if tok is _Operator, _AssignOp, or _IncOp
 
 	pragmas []Pragma
 }
@@ -119,6 +119,7 @@ redo:
 		c = s.getr()
 		if isDigit(c) {
 			s.ungetr()
+			s.source.r0-- // make sure '.' is part of literal (line cannot have changed)
 			s.number('.')
 			s.nlsemi = true
 			s.tok = _Literal
diff --git a/src/cmd/compile/internal/syntax/scanner_test.go b/src/cmd/compile/internal/syntax/scanner_test.go
index 9268cb35e0..2f78751740 100644
--- a/src/cmd/compile/internal/syntax/scanner_test.go
+++ b/src/cmd/compile/internal/syntax/scanner_test.go
@@ -34,3 +34,217 @@ func TestScanner(t *testing.T) {
 		}
 	}
 }
+
+func TestTokens(t *testing.T) {
+	// make source
+	var buf []byte
+	for i, s := range sampleTokens {
+		buf = append(buf, "\t\t\t\t"[:i&3]...)     // leading indentation
+		buf = append(buf, s.src...)                // token
+		buf = append(buf, "        "[:i&7]...)     // trailing spaces
+		buf = append(buf, "/* foo */ // bar\n"...) // comments
+	}
+
+	// scan source
+	var got scanner
+	got.init(&bytesReader{buf})
+	got.next()
+	for i, want := range sampleTokens {
+		nlsemi := false
+
+		if got.line != i+1 {
+			t.Errorf("got line %d; want %d", got.line, i+1)
+		}
+
+		if got.tok != want.tok {
+			t.Errorf("got tok = %s; want %s", got.tok, want.tok)
+			continue
+		}
+
+		switch want.tok {
+		case _Name, _Literal:
+			if got.lit != want.src {
+				t.Errorf("got lit = %q; want %q", got.lit, want.src)
+				continue
+			}
+			nlsemi = true
+
+		case _Operator, _AssignOp, _IncOp:
+			if got.op != want.op {
+				t.Errorf("got op = %s; want %s", got.op, want.op)
+				continue
+			}
+			if got.prec != want.prec {
+				t.Errorf("got prec = %s; want %s", got.prec, want.prec)
+				continue
+			}
+			nlsemi = want.tok == _IncOp
+
+		case _Rparen, _Rbrack, _Rbrace, _Break, _Continue, _Fallthrough, _Return:
+			nlsemi = true
+		}
+
+		if nlsemi {
+			got.next()
+			if got.tok != _Semi {
+				t.Errorf("got tok = %s; want ;", got.tok)
+				continue
+			}
+		}
+
+		got.next()
+	}
+
+	if got.tok != _EOF {
+		t.Errorf("got %q; want _EOF", got.tok)
+	}
+}
+
+var sampleTokens = [...]struct {
+	tok  token
+	src  string
+	op   Operator
+	prec int
+}{
+	// name samples
+	{_Name, "x", 0, 0},
+	{_Name, "X123", 0, 0},
+	{_Name, "foo", 0, 0},
+	{_Name, "Foo123", 0, 0},
+	{_Name, "foo_bar", 0, 0},
+	{_Name, "_", 0, 0},
+	{_Name, "_foobar", 0, 0},
+	{_Name, "a۰۱۸", 0, 0},
+	{_Name, "foo६४", 0, 0},
+	{_Name, "bar９８７６", 0, 0},
+	{_Name, "ŝ", 0, 0},
+	{_Name, "ŝfoo", 0, 0},
+
+	// literal samples
+	{_Literal, "0", 0, 0},
+	{_Literal, "1", 0, 0},
+	{_Literal, "12345", 0, 0},
+	{_Literal, "123456789012345678890123456789012345678890", 0, 0},
+	{_Literal, "01234567", 0, 0},
+	{_Literal, "0x0", 0, 0},
+	{_Literal, "0xcafebabe", 0, 0},
+	{_Literal, "0.", 0, 0},
+	{_Literal, "0.e0", 0, 0},
+	{_Literal, "0.e-1", 0, 0},
+	{_Literal, "0.e+123", 0, 0},
+	{_Literal, ".0", 0, 0},
+	{_Literal, ".0E00", 0, 0},
+	{_Literal, ".0E-0123", 0, 0},
+	{_Literal, ".0E+12345678901234567890", 0, 0},
+	{_Literal, ".45e1", 0, 0},
+	{_Literal, "3.14159265", 0, 0},
+	{_Literal, "1e0", 0, 0},
+	{_Literal, "1e+100", 0, 0},
+	{_Literal, "1e-100", 0, 0},
+	{_Literal, "2.71828e-1000", 0, 0},
+	{_Literal, "0i", 0, 0},
+	{_Literal, "1i", 0, 0},
+	{_Literal, "012345678901234567889i", 0, 0},
+	{_Literal, "123456789012345678890i", 0, 0},
+	{_Literal, "0.i", 0, 0},
+	{_Literal, ".0i", 0, 0},
+	{_Literal, "3.14159265i", 0, 0},
+	{_Literal, "1e0i", 0, 0},
+	{_Literal, "1e+100i", 0, 0},
+	{_Literal, "1e-100i", 0, 0},
+	{_Literal, "2.71828e-1000i", 0, 0},
+	{_Literal, "'a'", 0, 0},
+	{_Literal, "'\\000'", 0, 0},
+	{_Literal, "'\\xFF'", 0, 0},
+	{_Literal, "'\\uff16'", 0, 0},
+	{_Literal, "'\\U0000ff16'", 0, 0},
+	{_Literal, "`foobar`", 0, 0},
+	{_Literal, "`foo\tbar`", 0, 0},
+	{_Literal, "`\r`", 0, 0},
+
+	// operators
+	{_Operator, "||", OrOr, precOrOr},
+
+	{_Operator, "&&", AndAnd, precAndAnd},
+
+	{_Operator, "==", Eql, precCmp},
+	{_Operator, "!=", Neq, precCmp},
+	{_Operator, "<", Lss, precCmp},
+	{_Operator, "<=", Leq, precCmp},
+	{_Operator, ">", Gtr, precCmp},
+	{_Operator, ">=", Geq, precCmp},
+
+	{_Operator, "+", Add, precAdd},
+	{_Operator, "-", Sub, precAdd},
+	{_Operator, "|", Or, precAdd},
+	{_Operator, "^", Xor, precAdd},
+
+	{_Star, "*", Mul, precMul},
+	{_Operator, "/", Div, precMul},
+	{_Operator, "%", Rem, precMul},
+	{_Operator, "&", And, precMul},
+	{_Operator, "&^", AndNot, precMul},
+	{_Operator, "<<", Shl, precMul},
+	{_Operator, ">>", Shr, precMul},
+
+	// assignment operations
+	{_AssignOp, "+=", Add, precAdd},
+	{_AssignOp, "-=", Sub, precAdd},
+	{_AssignOp, "|=", Or, precAdd},
+	{_AssignOp, "^=", Xor, precAdd},
+
+	{_AssignOp, "*=", Mul, precMul},
+	{_AssignOp, "/=", Div, precMul},
+	{_AssignOp, "%=", Rem, precMul},
+	{_AssignOp, "&=", And, precMul},
+	{_AssignOp, "&^=", AndNot, precMul},
+	{_AssignOp, "<<=", Shl, precMul},
+	{_AssignOp, ">>=", Shr, precMul},
+
+	// other operations
+	{_IncOp, "++", Add, precAdd},
+	{_IncOp, "--", Sub, precAdd},
+	{_Assign, "=", 0, 0},
+	{_Define, ":=", 0, 0},
+	{_Arrow, "<-", 0, 0},
+
+	// delimiters
+	{_Lparen, "(", 0, 0},
+	{_Lbrack, "[", 0, 0},
+	{_Lbrace, "{", 0, 0},
+	{_Rparen, ")", 0, 0},
+	{_Rbrack, "]", 0, 0},
+	{_Rbrace, "}", 0, 0},
+	{_Comma, ",", 0, 0},
+	{_Semi, ";", 0, 0},
+	{_Colon, ":", 0, 0},
+	{_Dot, ".", 0, 0},
+	{_DotDotDot, "...", 0, 0},
+
+	// keywords
+	{_Break, "break", 0, 0},
+	{_Case, "case", 0, 0},
+	{_Chan, "chan", 0, 0},
+	{_Const, "const", 0, 0},
+	{_Continue, "continue", 0, 0},
+	{_Default, "default", 0, 0},
+	{_Defer, "defer", 0, 0},
+	{_Else, "else", 0, 0},
+	{_Fallthrough, "fallthrough", 0, 0},
+	{_For, "for", 0, 0},
+	{_Func, "func", 0, 0},
+	{_Go, "go", 0, 0},
+	{_Goto, "goto", 0, 0},
+	{_If, "if", 0, 0},
+	{_Import, "import", 0, 0},
+	{_Interface, "interface", 0, 0},
+	{_Map, "map", 0, 0},
+	{_Package, "package", 0, 0},
+	{_Range, "range", 0, 0},
+	{_Return, "return", 0, 0},
+	{_Select, "select", 0, 0},
+	{_Struct, "struct", 0, 0},
+	{_Switch, "switch", 0, 0},
+	{_Type, "type", 0, 0},
+	{_Var, "var", 0, 0},
+}