Initial commit

3 files changed, 139 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..134751d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+buforth
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..e4e97c1
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.kiefte.eu/lapingvino/buforth
+
+go 1.15
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..c6d1268
--- /dev/null
+++ b/main.go
@@ -0,0 +1,135 @@
+package main
+
+import (
+	"bufio"
+	"os"
+	"strings"
+	"strconv"
+)
+
+type operation func(*[]int, *int) string
+type numberError string
+type bufferError string
+
+func (n numberError) Error() string { return string(n) }
+func (n bufferError) Error() string { return string(n) }
+
+var stack []int
+var stackpointer int
+var dictionary = map[string]operation{
+	"base" : func(st *[]int, stp *int) string {
+		base, _ := getvalue(st, stp)
+		r, err := getvalue(st, stp)
+		if err != nil {
+			return err.Error()
+		}
+		return strconv.FormatInt(int64(r), base)
+	},
+	"+" : func(st *[]int, stp *int) string {
+		n1, _ := getvalue(st, stp)
+		n2, err := getvalue(st, stp)
+		if err != nil {
+			return err.Error()
+		}
+		err = putvalue(st, stp, n1+n2)
+		if err != nil {
+			return err.Error()
+		}
+		return "*"
+	},
+	"quit": func(_ *[]int, _ *int) string {
+		os.Exit(0)
+		return "should have quit"
+	},
+}
+
+func getvalue(st *[]int, stp *int) (int, error) {
+	if *stp < 1 {
+		return 0, bufferError("buffer underflow")
+	}
+	r := (*st)[*stp-1]
+	*st = (*st)[:len(*st)-1]
+	*stp--
+	return r, nil
+}
+
+func putvalue(st *[]int, stp *int, n int) error {
+	if *stp == int(^uint(0) >> 1) { // check for maxint
+		return bufferError("buffer overflow")
+	}
+	*st = append(*st, n)
+	*stp++
+	return nil
+}
+
+func read(r *bufio.Reader) (string, error) {
+	s, err := r.ReadString('\n')
+	if err != nil {
+		return "", err
+	}
+	return s[:len(s)-1], err
+}
+
+func pow(n, p int) int {
+	r := 1
+	for i := 0; i < p; i++ {
+		r *= n
+	}
+	return r
+}
+
+func number(st *[]int, stp *int, cmd string) error {
+	base := 6
+	if len(cmd) < 1 {
+		return numberError("tried parsing empty value")
+	}
+	switch {
+	case cmd[0] == 'd':
+		base = 10
+	case cmd[0] == 'x':
+		base = 16
+	case cmd[0] == '0':
+		base = 8
+	case cmd[0] == 'b':
+		base = 2
+	case cmd[0] == '#':
+		base = 36
+	}
+	if base != 6 {
+		cmd = cmd[1:]
+	}
+	val, err := strconv.ParseInt(cmd, base, 0)
+	if err != nil {
+		return err
+	}
+	return putvalue(st, stp, int(val))
+}
+
+func eval(code string, inerr error) string {
+	if inerr != nil {
+		return "Error before evaluating code: " + inerr.Error()
+	}
+	var value string
+	for _, cmd := range strings.Split(code, " ") {
+		op, ok := dictionary[cmd]
+		if ok {
+			value = op(&stack, &stackpointer)
+			continue
+		}
+		err := number(&stack, &stackpointer, cmd)
+		if err != nil {
+			return "Error reading value: " + err.Error()
+		}
+	}
+	return value
+}
+
+func main() {
+	stdin := bufio.NewReader(os.Stdin)
+	dictionary["."] = func(st *[]int, stp *int) string {
+		return eval("10 base", nil)
+	}
+	for {
+		println(eval(read(stdin)))
+	}
+}