Add a port to Go

1 files changed, 91 insertions, 0 deletions

diff --git a/cmd/repl/main.go b/cmd/repl/main.go
new file mode 100644
index 0000000..e7f35fb
--- /dev/null
+++ b/cmd/repl/main.go
@@ -0,0 +1,91 @@
+//
+// Copyright (c) 2018, Přemysl Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+// Program repl is an interactive ell interpreter.
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	// This library is rather simplistic but it's going to serve us fine.
+	"github.com/peterh/liner"
+
+	"janouch.name/ell/ell"
+)
+
+func run(L *ell.Ell, program *ell.V) {
+	var result *ell.V
+	if !L.EvalBlock(program, nil, &result) {
+		fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "runtime error", L.Error)
+		L.Error = ""
+	} else {
+		ell.PrintSeq(os.Stdout, result)
+		os.Stdout.WriteString("\n")
+	}
+}
+
+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)
+
+	line = strings.ToLower(line)
+	for v := L.Globals; v != nil; v = v.Next {
+		name := string(v.Head.String)
+		if strings.HasPrefix(strings.ToLower(name), line) {
+			res = append(res, name)
+		}
+	}
+	for name := range L.Native {
+		if strings.HasPrefix(strings.ToLower(name), line) {
+			res = append(res, name)
+		}
+	}
+	return
+}
+
+func main() {
+	L := ell.New()
+	if !ell.StdInitialize(L) {
+		fmt.Printf("runtime library initialization failed: %s\n", L.Error)
+	}
+
+	line := liner.NewLiner()
+	line.SetCompleter(func(line string) []string { return complete(L, line) })
+	line.SetMultiLineMode(true)
+	line.SetTabCompletionStyle(liner.TabPrints)
+
+	for {
+		script, err := line.Prompt("> ")
+		if err == nil {
+			line.AppendHistory(script)
+
+			p := ell.NewParser([]byte(script))
+			if program, err := p.Run(); err != nil {
+				fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "parse error", err)
+			} else {
+				run(L, program)
+			}
+		} else if err == liner.ErrPromptAborted || err == io.EOF {
+			break
+		} else {
+			fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "error", err)
+		}
+	}
+	os.Stdout.WriteString("\n")
+}