remove Atom. almost there

edn/src/iter.rs

@@ -0,0 +1,87 @@
+use crate::*;
+#[derive(Copy, Clone, Debug, PartialEq)] pub struct TokenIter<'a>(pub &'a str);
+const_iter!(<'a>|self: TokenIter<'a>| => Token<'a> => self.next_mut().map(|(result, _)|result));
+impl<'a> From<&'a str> for TokenIter<'a> {fn from (source: &'a str) -> Self{Self::new(source)}}
+impl<'a> TokenIter<'a> {
+    pub const fn new (source: &'a str) -> Self { Self(source) }
+    pub const fn chomp (&self, index: usize) -> Self { Self(split_at(self.0, index).1) }
+    pub const fn next (mut self) -> Option<(Token<'a>, Self)> { Self::next_mut(&mut self) }
+    pub const fn peek (&self) -> Option<Token<'a>> { peek_src(self.0) }
+    pub const fn next_mut (&mut self) -> Option<(Token<'a>, Self)> {
+        match self.peek() {
+            Some(token) => Some((token, self.chomp(token.end()))),
+            None => None
+        }
+    }
+}
+pub const fn peek_src <'a> (source: &'a str) -> Option<Token<'a>> {
+    let mut token: Token<'a> = Token::new(source, Nil, 0, 0);
+    iterate!(char_indices(source) => (start, c) => token = match token.value() {
+        Err(_) => return Some(token),
+        Nil => match c {
+            ' '|'\n'|'\r'|'\t' => token.grow(),
+            '(' => Token {
+                source, start, length: 1,
+                value: Value::Exp(1, TokenIter(str_range(source, start, start + 1))),
+            },
+            '0'..='9' => Token {
+                source, start, length: 1,
+                value: match to_digit(c) {
+                    Ok(c) => Value::Num(c),
+                    Result::Err(e) => Value::Err(e)
+                }
+            },
+            ':'|'@' => Token {
+                source, start, length: 1,
+                value: Value::Sym(str_range(source, start, start + 1)),
+            },
+            '/'|'a'..='z' => Token {
+                source, start, length: 1,
+                value: Value::Key(str_range(source, start, start + 1)),
+            },
+            _ => token.error(Unexpected(c))
+        },
+        Num(_) => match c {
+            '0'..='9' => token.grow(),
+            ' '|'\n'|'\r'|'\t' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Sym(_) => match c {
+            'a'..='z'|'0'..='9'|'-' => token.grow(),
+            ' '|'\n'|'\r'|'\t' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Key(_) => match c {
+            'a'..='z'|'0'..='9'|'-'|'/' => token.grow(),
+            ' '|'\n'|'\r'|'\t' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Exp(depth, _) => match depth {
+            0 => return Some(token),
+            _ => match c {
+                ')' => token.grow_out(),
+                '(' => token.grow_in(),
+                 _  => token.grow(),
+            }
+        },
+    });
+    match token.value() {
+        Nil => None,
+        _ => Some(token),
+    }
+}
+pub const fn to_number (digits: &str) -> Result<usize, ParseError> {
+    let mut value = 0;
+    iterate!(char_indices(digits) => (_, c) => match to_digit(c) {
+        Ok(digit) => value = 10 * value + digit,
+        Result::Err(e) => return Result::Err(e)
+    });
+    Ok(value)
+}
+pub const fn to_digit (c: char) -> Result<usize, ParseError> {
+    Ok(match c {
+        '0' => 0, '1' => 1, '2' => 2, '3' => 3, '4' => 4,
+        '5' => 5, '6' => 6, '7' => 7, '8' => 8, '9' => 9,
+        _ => return Result::Err(Unexpected(c))
+    })
+}