Added macros and the if macro

cmdlang/ast.go

@@ -8,13 +8,18 @@ import (
 
 type astLiteral struct {
 	Str *string `parser:"@String"`
-	Ident *string `parser:" | @Ident"`
+}
+
+type astBlock struct {
+	Statements []*astStatements `parser:"LC NL? @@ NL? RC"`
 }
 
 type astCmdArg struct {
 	Literal *astLiteral  `parser:"@@"`
+	Ident   *string      `parser:"| @Ident"`
 	Var     *string      `parser:"| DOLLAR @Ident"`
 	Sub     *astPipeline `parser:"| LP @@ RP"`
+	Block   *astBlock    `parser:"| @@"`
 }
 
 type astCmd struct {
@@ -29,29 +34,30 @@ type astPipeline struct {
 
 type astStatements struct {
 	First *astPipeline   `parser:"@@"`
-	Rest  []*astPipeline `parser:"( (SEMICL | NL)+ @@ )*"` // TODO: also add support for newlines
+	Rest  []*astPipeline `parser:"( NL+ @@ )*"` // TODO: also add support for newlines
 }
 
-type astBlock struct {
+type astScript struct {
-	Statements *astStatements `parser:"'{'  "`
+	Statements *astStatements `parser:"NL* @@ NL*"`
 }
 
 var scanner = lexer.MustStateful(lexer.Rules{
 	"Root": {
-		{"Whitespace", `[ ]`, nil},
+		{"Whitespace", `[ \t]+`, nil},
-		{"NL", `\n\s*`, nil},
 		{"String", `"(\\"|[^"])*"`, nil},
 		{"DOLLAR", `\$`, nil},
 		{"LP", `\(`, nil},
 		{"RP", `\)`, nil},
-		{"SEMICL", `;`, nil},
+		{"LC", `\{`, nil},
+		{"RC", `\}`, nil},
+		{"NL", `[;\n][; \n\t]*`, nil},
 		{"PIPE", `\|`, nil},
 		{"Ident", `\w+`, nil},
 	},
 })
-var parser = participle.MustBuild[astStatements](participle.Lexer(scanner),
+var parser = participle.MustBuild[astScript](participle.Lexer(scanner),
 	participle.Elide("Whitespace"))
 
-func parse(r io.Reader) (*astStatements, error) {
+func parse(r io.Reader) (*astScript, error) {
 	return parser.Parse("test", r)
 }

cmdlang/builtins.go

@@ -3,6 +3,7 @@ package cmdlang
 import (
 	"bufio"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -14,6 +15,7 @@ func echoBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 		if _, err := fmt.Fprintln(args.inst.Out()); err != nil {
 			return nil, err
 		}
+		return nil, nil
 	}
 
 	var line strings.Builder
@@ -83,6 +85,10 @@ func (f *fileLinesStream) String() string {
 	return fmt.Sprintf("fileLinesStream{file: %v}", f.filename)
 }
 
+func (f *fileLinesStream) Truthy() bool {
+	return true // ??
+}
+
 func (f *fileLinesStream) next() (object, error) {
 	var err error
 
@@ -111,25 +117,40 @@ func (f *fileLinesStream) close() error {
 	return nil
 }
 
-/*
+func ifBuiltin(ctx context.Context, args macroArgs) (object, error) {
-func errorTestBuiltin(ctx context.Context, inStream stream, args invocationArgs) (object, error) {
+	if args.nargs() < 2 {
-	return &timeBombStream{inStream, 2}, nil
+		return nil, errors.New("need at least 2 arguments")
-}
-
-type timeBombStream struct {
-	in stream
-	x  int
-}
-
-func (ms *timeBombStream) next() (object, error) {
-	if ms.x > 0 {
-		ms.x--
-		return ms.in.next()
 	}
-	return nil, errors.New("BOOM")
-}
 
-func (ms *timeBombStream) close() error {
+	if guard, err := args.evalArg(ctx, 0); err == nil && isTruthy(guard) {
-	return ms.in.close()
+		return args.evalBlock(ctx, 1)
+	} else if err != nil {
+		return nil, err
+	}
+
+	args.shift(2)
+	for args.identIs(ctx, 0, "elif") {
+		args.shift(1)
+
+		if args.nargs() < 2 {
+			return nil, errors.New("need at least 2 arguments")
+		}
+
+		if guard, err := args.evalArg(ctx, 0); err == nil && isTruthy(guard) {
+			return args.evalBlock(ctx, 1)
+		} else if err != nil {
+			return nil, err
+		}
+
+		args.shift(2)
+	}
+
+	if args.identIs(ctx, 0, "else") && args.nargs() > 1 {
+		return args.evalBlock(ctx, 1)
+	} else if args.nargs() == 0 {
+		// no elif or else
+		return nil, nil
+	}
+
+	return nil, errors.New("malformed if-elif-else")
 }
-*/

cmdlang/env.go

@@ -1,12 +1,9 @@
 package cmdlang
 
-import (
-	"errors"
-)
-
 type evalCtx struct {
 	parent   *evalCtx
 	commands map[string]invokable
+	macros   map[string]macroable
 	vars     map[string]object
 }
 
@@ -18,6 +15,14 @@ func (ec *evalCtx) addCmd(name string, inv invokable) {
 	ec.commands[name] = inv
 }
 
+func (ec *evalCtx) addMacro(name string, inv macroable) {
+	if ec.macros == nil {
+		ec.macros = make(map[string]macroable)
+	}
+
+	ec.macros[name] = inv
+}
+
 func (ec *evalCtx) setVar(name string, val object) {
 	if ec.vars == nil {
 		ec.vars = make(map[string]object)
@@ -39,16 +44,30 @@ func (ec *evalCtx) getVar(name string) (object, bool) {
 	return nil, false
 }
 
-func (ec *evalCtx) lookupCmd(name string) (invokable, error) {
+func (ec *evalCtx) lookupInvokable(name string) invokable {
+	if ec == nil {
+		return nil
+	}
+
 	for e := ec; e != nil; e = e.parent {
-		if e.commands == nil {
-			continue
-		}
-
 		if cmd, ok := e.commands[name]; ok {
-			return cmd, nil
+			return cmd
+		}
 	}
 
-	}
+	return ec.parent.lookupInvokable(name)
-	return nil, errors.New("name " + name + " not found")
+}
+
+func (ec *evalCtx) lookupMacro(name string) macroable {
+	if ec == nil {
+		return nil
+	}
+
+	for e := ec; e != nil; e = e.parent {
+		if cmd, ok := e.macros[name]; ok {
+			return cmd
+		}
+	}
+
+	return ec.parent.lookupMacro(name)
 }

cmdlang/eval.go

@@ -13,6 +13,22 @@ type evaluator struct {
 	inst *Inst
 }
 
+func (e evaluator) evalBlock(ctx context.Context, ec *evalCtx, n *astBlock) (lastRes object, err error) {
+	// TODO: push scope?
+
+	for _, s := range n.Statements {
+		lastRes, err = e.evalStatement(ctx, ec, s)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return lastRes, nil
+}
+
+func (e evaluator) evalScript(ctx context.Context, ec *evalCtx, n *astScript) (lastRes object, err error) {
+	return e.evalStatement(ctx, ec, n.Statements)
+}
+
 func (e evaluator) evalStatement(ctx context.Context, ec *evalCtx, n *astStatements) (object, error) {
 	res, err := e.evalPipeline(ctx, ec, n.First)
 	if err != nil {
@@ -60,11 +76,16 @@ func (e evaluator) evalPipeline(ctx context.Context, ec *evalCtx, n *astPipeline
 }
 
 func (e evaluator) evalCmd(ctx context.Context, ec *evalCtx, currentStream stream, ast *astCmd) (object, error) {
-	cmd, err := ec.lookupCmd(ast.Name)
+	if cmd := ec.lookupInvokable(ast.Name); cmd != nil {
-	if err != nil {
+		return e.evalInvokable(ctx, ec, currentStream, ast, cmd)
-		return nil, err
+	} else if macro := ec.lookupMacro(ast.Name); macro != nil {
+		return e.evalMacro(ctx, ec, currentStream, ast, macro)
 	}
 
+	return nil, errors.New("unknown command")
+}
+
+func (e evaluator) evalInvokable(ctx context.Context, ec *evalCtx, currentStream stream, ast *astCmd, cmd invokable) (object, error) {
 	args, err := slices.MapWithError(ast.Args, func(a astCmdArg) (object, error) {
 		return e.evalArg(ctx, ec, a)
 	})
@@ -87,18 +108,30 @@ func (e evaluator) evalCmd(ctx context.Context, ec *evalCtx, currentStream strea
 	return cmd.invoke(ctx, invArgs)
 }
 
+func (e evaluator) evalMacro(ctx context.Context, ec *evalCtx, currentStream stream, ast *astCmd, cmd macroable) (object, error) {
+	return cmd.invokeMacro(ctx, macroArgs{
+		eval:          e,
+		ec:            ec,
+		currentStream: currentStream,
+		ast:           ast,
+	})
+}
+
 func (e evaluator) evalArg(ctx context.Context, ec *evalCtx, n astCmdArg) (object, error) {
 	switch {
 	case n.Literal != nil:
 		return e.evalLiteral(ctx, ec, n.Literal)
+	case n.Ident != nil:
+		return strObject(*n.Ident), nil
 	case n.Var != nil:
-		v, ok := ec.getVar(*n.Var)
+		if v, ok := ec.getVar(*n.Var); ok {
-		if !ok {
-			return nil, fmt.Errorf("unknown variable %s", *n.Var)
-		}
 			return v, nil
+		}
+		return nil, nil
 	case n.Sub != nil:
 		return e.evalSub(ctx, ec, n.Sub)
+	case n.Block != nil:
+		return blockObject{block: n.Block}, nil
 	}
 	return nil, errors.New("unhandled arg type")
 }
@@ -111,8 +144,6 @@ func (e evaluator) evalLiteral(ctx context.Context, ec *evalCtx, n *astLiteral)
 			return nil, err
 		}
 		return strObject(uq), nil
-	case n.Ident != nil:
-		return strObject(*n.Ident), nil
 	}
 	return nil, errors.New("unhandled literal type")
 }

cmdlang/inst.go

@@ -31,6 +31,8 @@ func New(opts ...InstOption) *Inst {
 	rootEC.addCmd("toUpper", invokableStreamFunc(toUpperBuiltin))
 	rootEC.addCmd("cat", invokableFunc(catBuiltin))
 
+	rootEC.addMacro("if", macroFunc(ifBuiltin))
+
 	//rootEC.addCmd("testTimebomb", invokableStreamFunc(errorTestBuiltin))
 
 	rootEC.setVar("hello", strObject("world"))
@@ -76,7 +78,7 @@ func (inst *Inst) eval(ctx context.Context, expr string) (object, error) {
 
 	eval := evaluator{inst: inst}
 
-	return eval.evalStatement(ctx, inst.rootEC, ast)
+	return eval.evalScript(ctx, inst.rootEC, ast)
 }
 
 func (inst *Inst) EvalAndDisplay(ctx context.Context, expr string) error {

cmdlang/inst_test.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"github.com/lmika/cmdlang-proto/cmdlang"
 	"github.com/stretchr/testify/assert"
-	"strings"
 	"testing"
 )
 
@@ -38,8 +37,6 @@ func TestInst_Eval(t *testing.T) {
 		{desc: "multi 1", expr: `firstarg "hello" ; firstarg "world"`, want: "world"},
 		{desc: "multi 2", expr: `pipe "hello" | toUpper ; firstarg "world"`, want: "world"}, // TODO: assert for leaks
 		{desc: "multi 3", expr: `set new "this is new" ; firstarg $new`, want: "this is new"},
-
-		{desc: "multi-line 1", expr: "echo \"Hello\" \n echo \"world\"", want: "world"},
 	}
 
 	for _, tt := range tests {
@@ -56,7 +53,7 @@ func TestInst_Eval(t *testing.T) {
 	}
 }
 
-func TestInst_Builtins_Echo(t *testing.T) {
+func TestBuiltins_Echo(t *testing.T) {
 	tests := []struct {
 		desc string
 		expr string
@@ -65,8 +62,98 @@ func TestInst_Builtins_Echo(t *testing.T) {
 		{desc: "no args", expr: `echo`, want: "\n"},
 		{desc: "single arg", expr: `echo "hello"`, want: "hello\n"},
 		{desc: "dual args", expr: `echo "hello " "world"`, want: "hello world\n"},
-		{desc: "args to singleton stream", expr: `echo "aye" "bee" "see" | toUpper`, want: "AYEBEESEE\n"},
+		{desc: "multi-line 1", expr: `
-		{desc: "multi-line 1", expr: joinLines(`echo "Hello"`, `echo "world"`), want: "Hello\nworld"},
+			echo "Hello"
+			echo "world"
+		`, want: "Hello\nworld\n"},
+		{desc: "multi-line 2", expr: `
+			echo "Hello"
+
+
+			echo "world"
+		`, want: "Hello\nworld\n"},
+		{desc: "multi-line 3", expr: `
+
+;;;
+			echo "Hello"
+;
+
+			echo "world"
+;
+		`, want: "Hello\nworld\n"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			ctx := context.Background()
+			outW := bytes.NewBuffer(nil)
+
+			inst := cmdlang.New(cmdlang.WithOut(outW), cmdlang.WithTestBuiltin())
+			res, err := inst.Eval(ctx, tt.expr)
+
+			assert.NoError(t, err)
+			assert.Nil(t, res)
+			assert.Equal(t, tt.want, outW.String())
+		})
+	}
+}
+
+func TestBuiltins_If(t *testing.T) {
+	tests := []struct {
+		desc string
+		expr string
+		want string
+	}{
+		{desc: "single then", expr: `
+			set x "Hello"
+			if $x {
+				echo "true"
+			}`, want: "true\n(nil)\n"},
+		{desc: "single then and else", expr: `
+			set x "Hello"
+			if $x {
+				echo "true"
+			} else {
+				echo "false"
+			}`, want: "true\n(nil)\n"},
+		{desc: "single then, elif and else", expr: `
+			set x "Hello"
+			if $y {
+				echo "y is true"
+			} elif $x {
+				echo "x is true"
+			} else {
+				echo "nothings x"
+			}`, want: "x is true\n(nil)\n"},
+		{desc: "single then and elif, no else", expr: `
+			set x "Hello"
+			if $y {
+				echo "y is true"
+			} elif $x {
+				echo "x is true"
+			}`, want: "x is true\n(nil)\n"},
+		{desc: "single then, two elif, and else", expr: `
+			set x "Hello"
+			if $z {
+				echo "z is true"
+			} elif $y {
+				echo "y is true"
+			} elif $x {
+				echo "x is true"
+			}`, want: "x is true\n(nil)\n"},
+		{desc: "single then, two elif, and else, expecting else", expr: `
+			if $z {
+				echo "z is true"
+			} elif $y {
+				echo "y is true"
+			} elif $x {
+				echo "x is true"
+			} else {
+				echo "none is true"
+			}`, want: "none is true\n(nil)\n"},
+		{desc: "compressed then", expr: `set x "Hello" ; if $x { echo "true" }`, want: "true\n(nil)\n"},
+		{desc: "compressed else", expr: `if $x { echo "true" } else { echo "false" }`, want: "false\n(nil)\n"},
+		{desc: "compressed if", expr: `if $x { echo "x" } elif $y { echo "y" } else { echo "false" }`, want: "false\n(nil)\n"},
 	}
 
 	for _, tt := range tests {
@@ -82,7 +169,3 @@ func TestInst_Builtins_Echo(t *testing.T) {
 		})
 	}
 }
-
-func joinLines(ls ...string) string {
-	return strings.Join(ls, "\n")
-}

cmdlang/objs.go

@@ -9,6 +9,7 @@ import (
 
 type object interface {
 	String() string
+	Truthy() bool
 }
 
 type strObject string
@@ -17,6 +18,10 @@ func (s strObject) String() string {
 	return string(s)
 }
 
+func (s strObject) Truthy() bool {
+	return string(s) != ""
+}
+
 func toGoValue(obj object) (interface{}, bool) {
 	switch v := obj.(type) {
 	case nil:
@@ -28,6 +33,57 @@ func toGoValue(obj object) (interface{}, bool) {
 	return nil, false
 }
 
+type macroArgs struct {
+	eval          evaluator
+	ec            *evalCtx
+	currentStream stream
+	ast           *astCmd
+	argShift      int
+}
+
+func (ma macroArgs) nargs() int {
+	return len(ma.ast.Args[ma.argShift:])
+}
+
+func (ma *macroArgs) shift(n int) {
+	ma.argShift += n
+}
+
+func (ma macroArgs) identIs(ctx context.Context, n int, expectedIdent string) bool {
+	if n >= len(ma.ast.Args[ma.argShift:]) {
+		return false
+	}
+
+	lit := ma.ast.Args[ma.argShift+n].Ident
+	if lit == nil {
+		return false
+	}
+
+	return *lit == expectedIdent
+}
+
+func (ma macroArgs) evalArg(ctx context.Context, n int) (object, error) {
+	if n >= len(ma.ast.Args[ma.argShift:]) {
+		return nil, errors.New("not enough arguments") // FIX
+	}
+
+	return ma.eval.evalArg(ctx, ma.ec, ma.ast.Args[ma.argShift+n])
+}
+
+func (ma macroArgs) evalBlock(ctx context.Context, n int) (object, error) {
+	obj, err := ma.evalArg(ctx, n)
+	if err != nil {
+		return nil, err
+	}
+
+	block, ok := obj.(blockObject)
+	if !ok {
+		return nil, errors.New("not a block object")
+	}
+
+	return ma.eval.evalBlock(ctx, ma.ec, block.block)
+}
+
 type invocationArgs struct {
 	inst          *Inst
 	ec            *evalCtx
@@ -58,6 +114,10 @@ type invokable interface {
 	invoke(ctx context.Context, args invocationArgs) (object, error)
 }
 
+type macroable interface {
+	invokeMacro(ctx context.Context, args macroArgs) (object, error)
+}
+
 type streamInvokable interface {
 	invokable
 	invokeWithStream(context.Context, stream, invocationArgs) (object, error)
@@ -78,3 +138,28 @@ func (i invokableStreamFunc) invoke(ctx context.Context, args invocationArgs) (o
 func (i invokableStreamFunc) invokeWithStream(ctx context.Context, inStream stream, args invocationArgs) (object, error) {
 	return i(ctx, inStream, args)
 }
+
+type blockObject struct {
+	block *astBlock
+}
+
+func (bo blockObject) String() string {
+	return "block"
+}
+
+func (bo blockObject) Truthy() bool {
+	return len(bo.block.Statements) > 0
+}
+
+type macroFunc func(ctx context.Context, args macroArgs) (object, error)
+
+func (i macroFunc) invokeMacro(ctx context.Context, args macroArgs) (object, error) {
+	return i(ctx, args)
+}
+
+func isTruthy(obj object) bool {
+	if obj == nil {
+		return false
+	}
+	return obj.Truthy()
+}

cmdlang/streams.go

@@ -74,6 +74,10 @@ func (s *singletonStream) String() string {
 	return s.t.String()
 }
 
+func (s *singletonStream) Truthy() bool {
+	return !s.consumed
+}
+
 func (s *singletonStream) next() (object, error) {
 	if s.consumed {
 		return nil, io.EOF
@@ -93,6 +97,10 @@ func (s *listIterStream) String() string {
 	return fmt.Sprintf("listIterStream{list: %v}", s.list)
 }
 
+func (s *listIterStream) Truthy() bool {
+	return len(s.list) > s.cusr
+}
+
 func (s *listIterStream) next() (o object, err error) {
 	if s.cusr >= len(s.list) {
 		return nil, io.EOF
@@ -115,6 +123,10 @@ func (ms mapFilterStream) String() string {
 	return fmt.Sprintf("mapFilterStream{in: %v}", ms.in)
 }
 
+func (ms mapFilterStream) Truthy() bool {
+	return true // ???
+}
+
 func (ms mapFilterStream) next() (object, error) {
 	for {
 		u, err := ms.in.next()