From ea8c67dac9807b558b743951f9d85071a42b76ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Mart=C3=AD?= <mvdan@mvdan.cc>
Date: Wed, 31 Jul 2024 23:10:20 +0100
Subject: [PATCH] more

---
 example.go            | 76 +++++++++++++++++++++++++++++++++++++++++++
 syntax/parser_test.go |  4 +++
 syntax/walk.go        |  4 +++
 3 files changed, 84 insertions(+)
 create mode 100644 example.go

diff --git a/example.go b/example.go
new file mode 100644
index 00000000..1c640eac
--- /dev/null
+++ b/example.go
@@ -0,0 +1,76 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+
+	"mvdan.cc/sh/v3/syntax"
+)
+
+func main() {
+	src, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+	p := syntax.NewParser(syntax.RecoverErrors(5))
+	f, err := p.Parse(bytes.NewReader(src), "")
+	if err != nil {
+		panic(err)
+	}
+
+	last := lastStmt(f)
+	compl := extractCompletion(last, string(src))
+	fmt.Printf("%#v\n", compl)
+}
+
+func lastStmt(node syntax.Node) *syntax.Stmt {
+	var last *syntax.Stmt
+	// TODO: keep the first incomplete statement, too
+	syntax.Walk(node, func(node syntax.Node) bool {
+		if stmt, _ := node.(*syntax.Stmt); stmt != nil {
+			last = stmt
+		}
+		return true
+	})
+	return last
+}
+
+func extractCompletion(stmt *syntax.Stmt, src string) compResult {
+	syntax.DebugPrint(os.Stderr, stmt)
+	if len(stmt.Redirs) > 0 {
+		lastRedir := stmt.Redirs[len(stmt.Redirs)-1]
+		// fmt.Println(lastRedir.Word.Pos())
+		// fmt.Fprintln(os.Stderr, lastRedir.Word.Pos())
+		if lastRedir.Word.Pos().IsRecovered() {
+			return compResult{"redirect", nil}
+		}
+	}
+	if call, _ := stmt.Cmd.(*syntax.CallExpr); call != nil {
+		flat := flatWords(call.Args, src)
+		if stmt.End().Offset() < uint(len(src)) {
+			// Starting a new word.
+			flat = append(flat, "")
+		}
+		return compResult{"args", flat}
+	}
+
+	// other commands, e.g. "if foo; then bar; fi"
+	return compResult{}
+}
+
+func flatWords(words []*syntax.Word, src string) []string {
+	var flat []string
+	for _, word := range words {
+		start := word.Pos().Offset()
+		end := word.End().Offset()
+		flat = append(flat, src[start:end])
+	}
+	return flat
+}
+
+type compResult struct {
+	Type   string
+	Tokens []string
+}
diff --git a/syntax/parser_test.go b/syntax/parser_test.go
index 6cd097a1..ec7989de 100644
--- a/syntax/parser_test.go
+++ b/syntax/parser_test.go
@@ -2565,6 +2565,10 @@ func TestParseRecoverErrors(t *testing.T) {
 		// 	src:              "incomp >",
 		// 	wantRecoveredPos: 1,
 		// },
+		{
+			src:              "${incomp",
+			wantRecoveredPos: 1,
+		},
 		{
 			src:     "badsyntax)",
 			wantErr: true,
diff --git a/syntax/walk.go b/syntax/walk.go
index 27fdcb1b..8cfff744 100644
--- a/syntax/walk.go
+++ b/syntax/walk.go
@@ -291,6 +291,10 @@ func (p *debugPrinter) print(x reflect.Value) {
 
 	case reflect.Struct:
 		if v, ok := x.Interface().(Pos); ok {
+			if v.IsRecovered() {
+				p.printf("<recovered>")
+				return
+			}
 			p.printf("%v:%v", v.Line(), v.Col())
 			return
 		}