From 1ae1b9bb981f1c630ed5e68fa3bd1f937c6397ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C5=99emysl=20Janouch?= <p@janouch.name>
Date: Wed, 10 Oct 2018 15:40:18 +0200
Subject: Go/repl: improve completion

---
 cmd/repl/main.go | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/cmd/repl/main.go b/cmd/repl/main.go
index eb253d0..6d1f421 100644
--- a/cmd/repl/main.go
+++ b/cmd/repl/main.go
@@ -39,21 +39,24 @@ func run(L *ell.Ell, program *ell.V) {
 	}
 }
 
-func complete(L *ell.Ell, line string) (res []string) {
-	// This never actually completes anything, just shows the options,
-	// we'd have to figure out the longest common prefix.
-	res = append(res, line)
+func complete(L *ell.Ell, line string, pos int) (
+	head string, completions []string, tail string) {
+	tail = string([]rune(line)[pos:])
+
+	lastSpace := strings.LastIndexAny(string([]rune(line)[:pos]), " ()[]{};\n")
+	if lastSpace > -1 {
+		head, line = line[:lastSpace+1], line[lastSpace+1:]
+	}
 
-	line = strings.ToLower(line)
 	for v := L.Globals; v != nil; v = v.Next {
 		name := v.Head.String
 		if strings.HasPrefix(strings.ToLower(name), line) {
-			res = append(res, name)
+			completions = append(completions, name)
 		}
 	}
 	for name := range L.Native {
 		if strings.HasPrefix(strings.ToLower(name), line) {
-			res = append(res, name)
+			completions = append(completions, name)
 		}
 	}
 	return
@@ -66,7 +69,10 @@ func main() {
 	}
 
 	line := liner.NewLiner()
-	line.SetCompleter(func(line string) []string { return complete(L, line) })
+	line.SetWordCompleter(func(line string, pos int) (
+		string, []string, string) {
+		return complete(L, line, pos)
+	})
 	line.SetMultiLineMode(true)
 	line.SetTabCompletionStyle(liner.TabPrints)
 
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