Support completion of commands

edit/completion.go

@@ -6,6 +6,7 @@ import (
 	"path"
 	"strings"
 
+	"github.com/elves/elvish/eval"
 	"github.com/elves/elvish/parse"
 )
 
@@ -58,8 +59,8 @@ func (c *completion) next(cycle bool) {
 	}
 }
 
-func findCandidates(p string, all []string) (cands []*candidate) {
-	// Prefix match
+// Find candidates by matching against a prefix.
+func prefixMatchCandidates(p string, all []string) (cands []*candidate) {
 	for _, s := range all {
 		if len(s) >= len(p) && s[:len(p)] == p {
 			cand := newCandidate()
@@ -117,6 +118,8 @@ func peekCurrentCompound(ctx *parse.Context, dot int) (string, int, error) {
 	}
 
 	switch ctx.Typ {
+	case parse.CommandContext:
+		return peekIncompleteCompound(ctx.Form.Command)
 	case parse.ArgContext:
 		compounds := ctx.Form.Args.Nodes
 		lastCompound := compounds[len(compounds)-1]
@@ -134,6 +137,13 @@ func peekCurrentCompound(ctx *parse.Context, dot int) (string, int, error) {
 	}
 }
 
+var builtins []string
+
+func init() {
+	builtins = append(builtins, eval.BuiltinFnNames...)
+	builtins = append(builtins, eval.BuiltinSpecialNames...)
+}
+
 func startCompletion(ed *Editor, k Key) *leReturn {
 	c := &completion{}
 	ctx, err := parse.Complete("<completion>", ed.line[:ed.dot])
@@ -152,8 +162,13 @@ func startCompletion(ed *Editor, k Key) *leReturn {
 
 	switch ctx.Typ {
 	case parse.CommandContext:
-		// BUG(xiaq): When completing, CommandContext is not supported
-		ed.pushTip("command context not yet supported :(")
+		// BUG(xiaq): When completing commands, only builtins are searched
+		findAll = func() ([]string, error) {
+			return builtins, nil
+		}
+		makeCandidates = func(all []string) (cands []*candidate) {
+			return prefixMatchCandidates(compound, all)
+		}
 	case parse.NewArgContext, parse.ArgContext:
 		// BUG(xiaq): When completing, [New]ArgContext is treated like RedirFilenameContext
 		fallthrough

edit/writer.go

@@ -353,36 +353,38 @@ func (w *writer) refresh(bs *editorState) error {
 	}
 
 	comp := bs.completion
-	var suppress = false
+	hasComp := comp != nil && comp.current != -1
 
+	nowAt := func(i int) {
+		if hasComp && comp.start == i {
+			// Put the current completion candidate.
+			for _, part := range comp.candidates[comp.current].parts {
+				attr := attrForType[comp.typ]
+				if part.completed {
+					attr += attrForCompleted
+				}
+				b.writes(part.text, attr)
+			}
+		}
+		if bs.dot == i {
+			b.dot = b.cursor()
+		}
+	}
+	nowAt(0)
 tokens:
 	for _, token := range bs.tokens {
 		for _, r := range token.Val {
-			if suppress && i < comp.end {
+			if hasComp && comp.start <= i && i < comp.end {
 				// Silence the part that is being completed
 			} else {
 				b.write(r, attrForType[token.Typ])
 			}
 			i += utf8.RuneLen(r)
-			if comp != nil && comp.current != -1 && i == comp.start {
-				// Put the current candidate and instruct text up to comp.end
-				// to be suppressed. The cursor should be placed correctly
-				// (i.e. right after the candidate)
-				for _, part := range comp.candidates[comp.current].parts {
-					attr := attrForType[comp.typ]
-					if part.completed {
-						attr += attrForCompleted
-					}
-					b.writes(part.text, attr)
-				}
-				suppress = true
-			}
+
+			nowAt(i)
 			if bs.mode == modeHistory && i == len(bs.history.prefix) {
 				break tokens
 			}
-			if bs.dot == i {
-				b.dot = b.cursor()
-			}
 		}
 	}
 

eval/builtin_func.go

@@ -13,6 +13,7 @@ import (
 )
 
 var builtinFns []*builtinFn
+var BuiltinFnNames []string
 
 func init() {
 	// Needed to work around init loop.
@@ -51,6 +52,9 @@ func init() {
 
 		&builtinFn{"=", eq},
 	}
+	for _, b := range builtinFns {
+		BuiltinFnNames = append(BuiltinFnNames, b.Name)
+	}
 }
 
 var (

eval/builtin_special.go

@@ -19,6 +19,7 @@ type builtinSpecial struct {
 }
 
 var builtinSpecials map[string]builtinSpecial
+var BuiltinSpecialNames []string
 
 func init() {
 	// Needed to avoid initialization loop
@@ -34,6 +35,9 @@ func init() {
 
 		"static-typeof": builtinSpecial{compileStaticTypeof},
 	}
+	for k, _ := range builtinSpecials {
+		BuiltinSpecialNames = append(BuiltinSpecialNames, k)
+	}
 }
 
 func mayAssign(tvar, tval Type) bool {