104 lines
2.3 KiB
Go
104 lines
2.3 KiB
Go
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
// Context is a set of Dictionary + Stacks representing a runtime environment
|
|
type Context struct {
|
|
Dictionary Dictionary
|
|
Stack *Stack
|
|
RStack *Stack
|
|
}
|
|
|
|
// Eval evaulates a given line, recursively descending into given words as needed
|
|
func (c *Context) Eval(line string) error {
|
|
// state
|
|
var word []byte
|
|
var words []string
|
|
var comment bool
|
|
immediate := true
|
|
|
|
for i := 0; i < len(line); i = i + 1 {
|
|
switch line[i] {
|
|
case '(', ')': // comments
|
|
if len(word) == 0 {
|
|
if line[i] == '(' {
|
|
comment = true
|
|
continue
|
|
}
|
|
comment = false
|
|
continue
|
|
} else {
|
|
word = append(word, line[i])
|
|
}
|
|
case ':', ';': // COMPILE/IMMEDIATE mode swapping
|
|
if len(word) == 0 {
|
|
if line[i] == ':' {
|
|
immediate = false
|
|
} else if line[i-1] == ' ' && line[i] == ';' {
|
|
c.Dictionary.AddWord(words[0], nil, words[1:])
|
|
word = []byte{}
|
|
immediate = true
|
|
}
|
|
} else {
|
|
word = append(word, line[i])
|
|
}
|
|
case ' ':
|
|
if !immediate { // continue building our subroutine if we're not in immediate mode...
|
|
if len(word) != 0 { // don't add empty words to our list
|
|
words = append(words, strings.TrimSpace(string(word)))
|
|
word = []byte{}
|
|
}
|
|
continue
|
|
}
|
|
if len(word) == 0 || comment {
|
|
// empty space, just continue...
|
|
continue
|
|
}
|
|
|
|
int, err := strconv.Atoi(string(word))
|
|
if err == nil {
|
|
// it was a number! put it on the stack.
|
|
c.Stack.Push(int)
|
|
word = []byte{}
|
|
continue
|
|
}
|
|
|
|
// it wasn't a number. Is it a word we know?
|
|
w, err := c.Dictionary.GetWord(string(word))
|
|
if err != nil {
|
|
return fmt.Errorf("could not parse %s; %v", w.Name, err)
|
|
}
|
|
if w.Impl != nil {
|
|
// we have an implementation for that word. Run it.
|
|
err := w.Impl()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
word = []byte{}
|
|
} else if len(w.Source) != 0 {
|
|
// user-defined word; let's descend...
|
|
c.RStack.Push(i)
|
|
err := c.Eval(strings.Join(w.Source, " ") + " ")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
i, err = c.RStack.Pop()
|
|
if err != nil {
|
|
return fmt.Errorf("error while popping from return stack: %v", err)
|
|
}
|
|
word = []byte{}
|
|
}
|
|
default:
|
|
if !comment {
|
|
word = append(word, line[i])
|
|
}
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|