compile: Implement if expression and JUMP_FORWARD

ncw · ncw · commit d7653f2434e9 · 2015-03-24T08:38:32.000Z
diff --git a/compile/compile.go b/compile/compile.go
@@ -173,7 +173,7 @@ func (c *compiler) Jump(Op byte, Dest *Label) {
 	case vm.JUMP_IF_FALSE_OR_POP, vm.JUMP_IF_TRUE_OR_POP, vm.JUMP_ABSOLUTE, vm.POP_JUMP_IF_FALSE, vm.POP_JUMP_IF_TRUE: // Absolute
 		c.OpCodes.Add(&JumpAbs{OpArg: OpArg{Op: Op}, Dest: Dest})
 	case vm.JUMP_FORWARD: // Relative
-		panic("FIXME JUMP_FORWARD NOT implemented")
+		c.OpCodes.Add(&JumpRel{OpArg: OpArg{Op: Op}, Dest: Dest})
 	default:
 		panic("Jump called with non jump instruction")
 	}
@@ -368,7 +368,15 @@ func (c *compiler) compileExpr(expr ast.Expr) {
 		// Test   Expr
 		// Body   Expr
 		// Orelse Expr
-		panic("FIXME not implemented")
+		elseBranch := new(Label)
+		endifBranch := new(Label)
+		c.compileExpr(node.Test)
+		c.Jump(vm.POP_JUMP_IF_FALSE, elseBranch)
+		c.compileExpr(node.Body)
+		c.Jump(vm.JUMP_FORWARD, endifBranch)
+		c.Label(elseBranch)
+		c.compileExpr(node.Body)
+		c.Label(endifBranch)
 	case *ast.Dict:
 		// Keys   []Expr
 		// Values []Expr
@@ -471,7 +479,8 @@ func (is Instructions) Pass(pass int) bool {
 	addr := uint32(0)
 	changed := false
 	for _, i := range is {
-		changed = changed || i.SetPos(addr)
+		posChanged := i.SetPos(addr)
+		changed = changed || posChanged
 		if pass > 0 {
 			// Only resolve addresses on 2nd pass
 			if resolver, ok := i.(Resolver); ok {
@@ -595,4 +604,25 @@ func (o *JumpAbs) Resolve() {
 	o.OpArg.Arg = o.Dest.Pos()
 }
 
-// FIXME Jump Relative
+// A relative JUMP with destination label
+type JumpRel struct {
+	pos
+	OpArg
+	Dest *Label
+}
+
+// Set the Arg from the Jump Label
+func (o *JumpRel) Resolve() {
+	currentSize := o.Size()
+	currentPos := o.Pos() + currentSize
+	if o.Dest.Pos() < currentPos {
+		panic("Attempt use JUMP_FORWARD to jump backwards")
+	}
+	o.OpArg.Arg = o.Dest.Pos() - currentPos
+	if o.Size() != currentSize {
+		// There is an awkward moment where jump forwards is
+		// between 0x1000 and 0x1002 where the Arg oscillates
+		// between 2 and 4 bytes
+		panic("FIXME JUMP_FOWARDS size changed")
+	}
+}
diff --git a/compile/compile_data_test.go b/compile/compile_data_test.go
@@ -403,4 +403,72 @@ var compileTestData = []struct {
 		Firstlineno:    1,
 		Lnotab:         "",
 	}, "  1           0 LOAD_CONST               0 (1)\n              3 JUMP_IF_TRUE_OR_POP     21\n              6 LOAD_CONST               1 (2)\n              9 JUMP_IF_TRUE_OR_POP     21\n             12 LOAD_CONST               2 (3)\n             15 JUMP_IF_TRUE_OR_POP     21\n             18 LOAD_CONST               3 (4)\n        >>   21 RETURN_VALUE\n"},
+	{"\"1\"+\"2\"*\"3\"", "eval", py.Code{
+		Argcount:       0,
+		Kwonlyargcount: 0,
+		Nlocals:        0,
+		Stacksize:      3,
+		Flags:          64,
+		Code:           "\x64\x00\x00\x64\x01\x00\x64\x02\x00\x14\x17\x53",
+		Consts:         []py.Object{py.String("1"), py.String("2"), py.String("3")},
+		Names:          []string{},
+		Varnames:       []string{},
+		Freevars:       []string{},
+		Cellvars:       []string{},
+		Filename:       "<string>",
+		Name:           "<module>",
+		Firstlineno:    1,
+		Lnotab:         "",
+	}, "  1           0 LOAD_CONST               0 ('1')\n              3 LOAD_CONST               1 ('2')\n              6 LOAD_CONST               2 ('3')\n              9 BINARY_MULTIPLY\n             10 BINARY_ADD\n             11 RETURN_VALUE\n"},
+	{"\"1\"+(\"2\"*\"3\")", "eval", py.Code{
+		Argcount:       0,
+		Kwonlyargcount: 0,
+		Nlocals:        0,
+		Stacksize:      3,
+		Flags:          64,
+		Code:           "\x64\x00\x00\x64\x01\x00\x64\x02\x00\x14\x17\x53",
+		Consts:         []py.Object{py.String("1"), py.String("2"), py.String("3")},
+		Names:          []string{},
+		Varnames:       []string{},
+		Freevars:       []string{},
+		Cellvars:       []string{},
+		Filename:       "<string>",
+		Name:           "<module>",
+		Firstlineno:    1,
+		Lnotab:         "",
+	}, "  1           0 LOAD_CONST               0 ('1')\n              3 LOAD_CONST               1 ('2')\n              6 LOAD_CONST               2 ('3')\n              9 BINARY_MULTIPLY\n             10 BINARY_ADD\n             11 RETURN_VALUE\n"},
+	{"(1+\"2\")*\"3\"", "eval", py.Code{
+		Argcount:       0,
+		Kwonlyargcount: 0,
+		Nlocals:        0,
+		Stacksize:      2,
+		Flags:          64,
+		Code:           "\x64\x00\x00\x64\x01\x00\x17\x64\x02\x00\x14\x53",
+		Consts:         []py.Object{py.Int(1), py.String("2"), py.String("3")},
+		Names:          []string{},
+		Varnames:       []string{},
+		Freevars:       []string{},
+		Cellvars:       []string{},
+		Filename:       "<string>",
+		Name:           "<module>",
+		Firstlineno:    1,
+		Lnotab:         "",
+	}, "  1           0 LOAD_CONST               0 (1)\n              3 LOAD_CONST               1 ('2')\n              6 BINARY_ADD\n              7 LOAD_CONST               2 ('3')\n             10 BINARY_MULTIPLY\n             11 RETURN_VALUE\n"},
+	{"(\"true\" if 1+\"2\" else \"false\")+\"a\"", "eval", py.Code{
+		Argcount:       0,
+		Kwonlyargcount: 0,
+		Nlocals:        0,
+		Stacksize:      2,
+		Flags:          64,
+		Code:           "\x64\x00\x00\x64\x01\x00\x17\x72\x10\x00\x64\x02\x00\x6e\x03\x00\x64\x03\x00\x64\x04\x00\x17\x53",
+		Consts:         []py.Object{py.Int(1), py.String("2"), py.String("true"), py.String("false"), py.String("a")},
+		Names:          []string{},
+		Varnames:       []string{},
+		Freevars:       []string{},
+		Cellvars:       []string{},
+		Filename:       "<string>",
+		Name:           "<module>",
+		Firstlineno:    1,
+		Lnotab:         "",
+	}, "  1           0 LOAD_CONST               0 (1)\n              3 LOAD_CONST               1 ('2')\n              6 BINARY_ADD\n              7 POP_JUMP_IF_FALSE       16\n             10 LOAD_CONST               2 ('true')\n             13 JUMP_FORWARD             3 (to 19)\n        >>   16 LOAD_CONST               3 ('false')\n        >>   19 LOAD_CONST               4 ('a')\n             22 BINARY_ADD\n             23 RETURN_VALUE\n"},
 }
diff --git a/compile/make_compile_test.py b/compile/make_compile_test.py
@@ -35,6 +35,12 @@
     ('''1 and 2''', "eval"),
     ('''1 or 2''', "eval"),
     ('''1 or 2 or 3 or 4''', "eval"),
+    # With brackets
+    ('''"1"+"2"*"3"''', "eval"),
+    ('''"1"+("2"*"3")''', "eval"),
+    ('''(1+"2")*"3"''', "eval"),
+    # If expression
+    ('''("true" if 1+"2" else "false")+"a"''', "eval"),
 
 ]
 
