refactor to use an interface instead of buildCmd

lang/common.go

@@ -1,17 +0,0 @@
-package lang
-
-// Commonly used Terms
-var (
-	// Language structure types
-	AAtom  = Atom("atom")
-	AConst = Atom("const")
-	ATuple = Atom("tup")
-	AList  = Atom("list")
-
-	// Match shortcuts
-	AUnder    = Atom("_")
-	TDblUnder = Tuple{AUnder, AUnder}
-
-	// VM commands
-	AAdd = Atom("add")
-)

lang/lang.go

@@ -6,6 +6,19 @@ import (
 	"strings"
 )
 
+// Commonly used Terms
+var (
+	// Language structure types
+	AAtom  = Atom("atom")
+	AConst = Atom("const")
+	ATuple = Atom("tup")
+	AList  = Atom("list")
+
+	// Match shortcuts
+	AUnder    = Atom("_")
+	TDblUnder = Tuple{AUnder, AUnder}
+)
+
 // Term is a unit of language which carries some meaning. Some Terms are
 // actually comprised of multiple sub-Terms.
 type Term interface {
@@ -33,7 +46,7 @@ func (a Atom) String() string {
 
 // Type implements the method for Term
 func (a Atom) Type() Term {
-	return Atom("atom")
+	return AAtom
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -47,7 +60,7 @@ func (a Const) String() string {
 
 // Type implements the method for Term
 func (a Const) Type() Term {
-	return Const("const")
+	return AConst
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -71,7 +84,7 @@ func (t Tuple) Type() Term {
 	for i := range t {
 		tt[i] = t[i].Type()
 	}
-	return Tuple{Atom("tup"), tt}
+	return Tuple{ATuple, tt}
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -101,5 +114,5 @@ func (l list) String() string {
 
 // Type implements the method for Term
 func (l list) Type() Term {
-	return Tuple{Atom("list"), l.typ}
+	return Tuple{AList, l.typ}
 }

main.go

@@ -8,10 +8,10 @@ import (
 )
 
 func main() {
-	t := lang.Tuple{lang.AAdd, lang.Tuple{
+	t := lang.Tuple{vm.Add, lang.Tuple{vm.Tuple, lang.Tuple{
 		lang.Tuple{vm.Int, lang.Const("1")},
 		lang.Tuple{vm.Int, lang.Const("2")},
-	}}
+	}}}
 
 	mod, err := vm.Build(t)
 	if err != nil {

vm/cmds.go

@@ -1,42 +1,119 @@
 package vm
 
 import (
+	"errors"
+	"fmt"
 	"strconv"
 
 	"github.com/mediocregopher/ginger/lang"
 	"llvm.org/llvm/bindings/go/llvm"
 )
 
-type buildCmd struct {
+type cmd interface {
-	pattern   lang.Tuple
+	inType() valType
-	inTypeFn  func(lang.Term) (llvm.Type, error)
+	outType() valType
-	outTypeFn func(lang.Term) (llvm.Type, error)
+	build(*Module) (llvm.Value, error)
-	buildFn   func(lang.Term) (val, error)
 }
 
-func (cmd buildCmd) matches(t lang.Term) bool {
+type valType struct {
-	return lang.Match(cmd.pattern, t)
+	term lang.Term
+	llvm llvm.Type
 }
 
-func (cmd buildCmd) inType(t lang.Term) (llvm.Type, error) {
+// most types don't have an input, so we use this as a shortcut
-	if cmd.inTypeFn == nil {
+type voidIn struct{}
-		return llvm.VoidType(), nil
+
+func (voidIn) inType() valType {
+	return valType{
+		term: lang.Tuple{},
+		llvm: llvm.VoidType(),
 	}
-	return cmd.inTypeFn(t)
 }
 
-func (cmd buildCmd) outType(t lang.Term) (llvm.Type, error) {
+////////////////////////////////////////////////////////////////////////////////
-	if cmd.outTypeFn == nil {
+
-		return llvm.VoidType(), nil
+type intCmd struct {
-	}
+	voidIn
-	return cmd.outTypeFn(t)
+	c lang.Const
 }
 
-func (cmd buildCmd) build(t lang.Term) (val, error) {
+func (ic intCmd) outType() valType {
-	return cmd.buildFn(t)
+	return valType{
+		term: Int,
+		llvm: llvm.Int64Type(),
+	}
 }
 
-func buildCmds(mod *Module) []buildCmd {
+func (ic intCmd) build(mod *Module) (llvm.Value, error) {
+	ci, err := strconv.ParseInt(string(ic.c), 10, 64)
+	if err != nil {
+		return llvm.Value{}, err
+	}
+	return llvm.ConstInt(llvm.Int64Type(), uint64(ci), false), nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+type tupCmd struct {
+	voidIn
+	els []cmd
+}
+
+func (tc tupCmd) outType() valType {
+	termTypes := make(lang.Tuple, len(tc.els))
+	llvmTypes := make([]llvm.Type, len(tc.els))
+	for i := range tc.els {
+		elValType := tc.els[i].outType()
+		termTypes[i] = elValType.term
+		llvmTypes[i] = elValType.llvm
+	}
+	vt := valType{term: lang.Tuple{Tuple, termTypes}}
+	if len(llvmTypes) == 0 {
+		vt.llvm = llvm.VoidType()
+	} else {
+		vt.llvm = llvm.StructType(llvmTypes, false)
+	}
+	return vt
+}
+
+func (tc tupCmd) build(mod *Module) (llvm.Value, error) {
+	str := llvm.Undef(tc.outType().llvm)
+	var val llvm.Value
+	var err error
+	for i := range tc.els {
+		if val, err = tc.els[i].build(mod); err != nil {
+			str = mod.b.CreateInsertValue(str, val, i, "")
+		}
+	}
+	return str, err
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+type addCmd struct {
+	voidIn
+	a, b intCmd
+}
+
+func (ac addCmd) outType() valType {
+	return ac.a.outType()
+}
+
+func (ac addCmd) build(mod *Module) (llvm.Value, error) {
+	av, err := ac.a.build(mod)
+	if err != nil {
+		return llvm.Value{}, err
+	}
+	bv, err := ac.b.build(mod)
+	if err != nil {
+		return llvm.Value{}, err
+	}
+	return mod.b.CreateAdd(av, bv, ""), nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+func matchCmd(t lang.Term) (cmd, error) {
 	aPat := func(a lang.Atom) lang.Tuple {
 		return lang.Tuple{lang.AAtom, a}
 	}
@@ -46,98 +123,58 @@ func buildCmds(mod *Module) []buildCmd {
 	tPat := func(el ...lang.Term) lang.Tuple {
 		return lang.Tuple{Tuple, lang.Tuple(el)}
 	}
-	buildPat := func(a lang.Atom, b lang.Tuple) lang.Tuple {
-		return tPat(aPat(a), b)
-	}
-	return []buildCmd{
-		{ // (int 42)
-			pattern: buildPat(Int, cPat(lang.AUnder)),
-			outTypeFn: func(t lang.Term) (llvm.Type, error) {
-				return llvm.Int64Type(), nil
-			},
-			buildFn: func(t lang.Term) (val, error) {
-				con := t.(lang.Const)
-				coni, err := strconv.ParseInt(string(con), 10, 64)
-				if err != nil {
-					return val{}, err
-				}
-				return val{
-					// TODO why does this have to be cast?
-					v:   llvm.ConstInt(llvm.Int64Type(), uint64(coni), false),
-					typ: Int,
-				}, nil
-			},
-		},
 
-		{ // (tup ((atom foo) (const 10)))
+	if !lang.Match(tPat(aPat(lang.AUnder), lang.TDblUnder), t) {
-			pattern: buildPat(Tuple, lang.Tuple{Tuple, lang.AUnder}),
+		return nil, fmt.Errorf("term %v does not look like a vm command", t)
-			outTypeFn: func(t lang.Term) (llvm.Type, error) {
-				tup := t.(lang.Tuple)
-				if len(tup) == 0 {
-					return llvm.VoidType(), nil
 	}
+	k := t.(lang.Tuple)[0].(lang.Atom)
+	v := t.(lang.Tuple)[1]
+
+	// for when v is a Tuple argument, convenience function for casting
+	vAsTup := func(n int) ([]cmd, error) {
+		vcmd, err := matchCmd(v)
+		if err != nil {
+			return nil, err
+		}
+		vtup, ok := vcmd.(tupCmd)
+		if !ok || len(vtup.els) != n {
+			return nil, fmt.Errorf("cmd %v expects a %d-tuple argument", k, n)
+		}
+		return vtup.els, nil
+	}
+
+	switch k {
+	case Int:
+		if !lang.Match(cPat(lang.AUnder), v) {
+			return nil, errors.New("int requires constant arg")
+		}
+		return intCmd{c: v.(lang.Const)}, nil
+	case Tuple:
+		if !lang.Match(lang.Tuple{Tuple, lang.AUnder}, v) {
+			return nil, errors.New("tup requires tuple arg")
+		}
+		tup := v.(lang.Tuple)
+		tc := tupCmd{els: make([]cmd, len(tup))}
 		var err error
-				typs := make([]llvm.Type, len(tup))
 		for i := range tup {
-					if typs[i], err = mod.outType(tup[i]); err != nil {
+			if tc.els[i], err = matchCmd(tup[i]); err != nil {
-						return llvm.Type{}, err
+				return nil, err
 			}
 		}
-				return llvm.StructType(typs, false), nil
+		return tc, nil
-			},
+	case Add:
-			buildFn: func(t lang.Term) (val, error) {
+		els, err := vAsTup(2)
-				tup := t.(lang.Tuple)
-				// if the tuple is empty then it is a void
-				if len(tup) == 0 {
-					return val{
-						v:   llvm.Undef(llvm.VoidType()),
-						typ: lang.Tuple{Tuple, lang.Tuple{}},
-					}, nil
-				}
-
-				var err error
-				vals := make([]val, len(tup))
-				typs := make([]llvm.Type, len(tup))
-				ttyps := make([]lang.Term, len(tup))
-				for i := range tup {
-					if vals[i], err = mod.build(tup[i]); err != nil {
-						return val{}, err
-					}
-					typs[i] = vals[i].v.Type()
-					ttyps[i] = vals[i].typ
-				}
-
-				str := llvm.Undef(llvm.StructType(typs, false))
-				for i := range vals {
-					str = mod.b.CreateInsertValue(str, vals[i].v, i, "")
-				}
-				return val{
-					v:   str,
-					typ: lang.Tuple{Tuple, lang.Tuple(ttyps)},
-				}, nil
-			},
-		},
-
-		{ // (add ((const 5) (var foo)))
-			pattern: buildPat(lang.AAdd, tPat(lang.TDblUnder, lang.TDblUnder)),
-			outTypeFn: func(t lang.Term) (llvm.Type, error) {
-				return llvm.Int64Type(), nil
-			},
-			buildFn: func(t lang.Term) (val, error) {
-				tup := t.(lang.Tuple)
-				v1, err := mod.build(tup[0])
 		if err != nil {
-					return val{}, err
+			return nil, err
+		} else if _, ok := els[0].(intCmd); !ok {
+			return nil, errors.New("add args must be numbers")
+		} else if _, ok := els[1].(intCmd); !ok {
+			return nil, errors.New("add args must be numbers")
+		} else if !lang.Equal(els[0].outType().term, els[1].outType().term) {
+			return nil, errors.New("add args must be the same type")
 		}
-				v2, err := mod.build(tup[1])
+		return addCmd{a: els[0].(intCmd), b: els[1].(intCmd)}, nil
-				if err != nil {
+	default:
-					return val{}, err
+		return nil, fmt.Errorf("cmd %v unknown, or its args are malformed", t)
-				}
-				return val{
-					v:   mod.b.CreateAdd(v1.v, v2.v, ""),
-					typ: v1.typ,
-				}, nil
-			},
-		},
 	}
 }

vm/types.go

@@ -1,44 +0,0 @@
-package vm
-
-import (
-	"fmt"
-
-	"github.com/mediocregopher/ginger/lang"
-	"llvm.org/llvm/bindings/go/llvm"
-)
-
-// Types supported by the vm in addition to those which are part of lang
-var (
-	Atom  = lang.AAtom
-	Tuple = lang.ATuple
-	Int   = lang.Atom("int")
-)
-
-var (
-	tupPat = lang.Tuple{lang.ATuple, lang.Tuple{
-		lang.Tuple{lang.AAtom, Tuple},
-		lang.Tuple{lang.ATuple, lang.AUnder},
-	}}
-)
-
-func termToType(t lang.Term) (llvm.Type, error) {
-	switch {
-	case lang.Equal(t, Int):
-		return llvm.Int64Type(), nil
-	case lang.Match(tupPat, t):
-		tup := t.(lang.Tuple)[1].(lang.Tuple)
-		if len(tup) == 0 {
-			return llvm.VoidType(), nil
-		}
-		var err error
-		typs := make([]llvm.Type, len(tup))
-		for i := range tup {
-			if typs[i], err = termToType(tup[i]); err != nil {
-				return llvm.Type{}, err
-			}
-		}
-		return llvm.StructType(typs, false), nil
-	default:
-		return llvm.Type{}, fmt.Errorf("type %v not supported", t)
-	}
-}

vm/vm.go

@@ -10,10 +10,17 @@ import (
 	"llvm.org/llvm/bindings/go/llvm"
 )
 
-type val struct {
+// Types supported by the vm in addition to those which are part of lang
-	typ lang.Term
+var (
-	v   llvm.Value
+	Atom  = lang.AAtom
-}
+	Tuple = lang.ATuple
+	Int   = lang.Atom("int")
+)
+
+// Commands supported by the vm. Each of the types are also commands
+var (
+	Add = lang.Atom("add")
+)
 
 // Module contains a compiled set of code which can be run, dumped in IR form,
 // or compiled. A Module should be Dispose()'d of once it's no longer being
@@ -22,7 +29,6 @@ type Module struct {
 	b      llvm.Builder
 	m      llvm.Module
 	mainFn llvm.Value
-	buildCmds []buildCmd
 }
 
 var initOnce sync.Once
@@ -38,7 +44,6 @@ func Build(t lang.Term) (*Module, error) {
 		b: llvm.NewBuilder(),
 		m: llvm.NewModule(""),
 	}
-	mod.buildCmds = buildCmds(mod)
 
 	var err error
 	if mod.mainFn, err = mod.buildFn(t); err != nil {
@@ -61,73 +66,39 @@ func (mod *Module) Dispose() {
 	//mod.b.Dispose()
 }
 
-func (mod *Module) matchingBuildCmd(t lang.Term) (buildCmd, error) {
-	for _, cmd := range mod.buildCmds {
-		if !cmd.matches(t) {
-			continue
-		}
-		return cmd, nil
-	}
-	return buildCmd{}, fmt.Errorf("unknown compiler command %v", t)
-}
-
-func (mod *Module) inType(t lang.Term) (llvm.Type, error) {
-	cmd, err := mod.matchingBuildCmd(t)
-	if err != nil {
-		return llvm.Type{}, err
-	}
-	return cmd.inType(t.(lang.Tuple)[1])
-}
-
-func (mod *Module) outType(t lang.Term) (llvm.Type, error) {
-	cmd, err := mod.matchingBuildCmd(t)
-	if err != nil {
-		return llvm.Type{}, err
-	}
-	return cmd.outType(t.(lang.Tuple)[1])
-}
-
-func (mod *Module) build(t lang.Term) (val, error) {
-	cmd, err := mod.matchingBuildCmd(t)
-	if err != nil {
-		return val{}, err
-	}
-	return cmd.build(t.(lang.Tuple)[1])
-}
-
 // TODO make this return a val once we get function types
 func (mod *Module) buildFn(tt ...lang.Term) (llvm.Value, error) {
 	if len(tt) == 0 {
 		return llvm.Value{}, errors.New("function cannot be empty")
 	}
 
-	inType, err := mod.inType(tt[0])
+	cmds := make([]cmd, len(tt))
-	if err != nil {
+	var err error
+	for i := range tt {
+		if cmds[i], err = matchCmd(tt[i]); err != nil {
 			return llvm.Value{}, err
 		}
-	var inTypes []llvm.Type
+	}
-	if inType.TypeKind() == llvm.VoidTypeKind {
+
-		inTypes = []llvm.Type{}
+	var llvmIns []llvm.Type
+	if in := cmds[0].inType(); in.llvm.TypeKind() == llvm.VoidTypeKind {
+		llvmIns = []llvm.Type{}
 	} else {
-		inTypes = []llvm.Type{inType}
+		llvmIns = []llvm.Type{in.llvm}
 	}
+	llvmOut := cmds[len(cmds)-1].outType().llvm
 
-	outType, err := mod.outType(tt[len(tt)-1])
+	fn := llvm.AddFunction(mod.m, "", llvm.FunctionType(llvmOut, llvmIns, false))
-	if err != nil {
-		return llvm.Value{}, err
-	}
-
-	fn := llvm.AddFunction(mod.m, "", llvm.FunctionType(outType, inTypes, false))
 	block := llvm.AddBasicBlock(fn, "")
 	mod.b.SetInsertPoint(block, block.FirstInstruction())
 
-	var out val
+	var out llvm.Value
-	for _, t := range tt {
+	for i := range cmds {
-		if out, err = mod.build(t); err != nil {
+		if out, err = cmds[i].build(mod); err != nil {
-			return llvm.Value{}, err
+			return llvm.Value{}, nil
 		}
 	}
-	mod.b.CreateRet(out.v)
+	mod.b.CreateRet(out)
 	return fn, nil
 }