dsl goes fat

dsl/src/dsl_cst.rs

@@ -1,12 +1,183 @@
 use crate::*;
+
 /// CST stores strings as source references and expressions as new [SourceIter] instances.
 pub type CstValue<'source> = Value<&'source str, SourceIter<'source>>;
-/// Token sharing memory with source reference.
-#[derive(Debug, Copy, Clone, Default, PartialEq)]
-pub struct CstToken<'source>(pub CstValue<'source>, pub CstMeta<'source>);
+
 /// Reference to the source slice.
 #[derive(Debug, Copy, Clone, Default, PartialEq)] pub struct CstMeta<'source> {
     pub source: &'source str,
     pub start:  usize,
     pub length: usize,
 }
+
+/// Token sharing memory with source reference.
+#[derive(Debug, Copy, Clone, Default, PartialEq)]
+pub struct CstToken<'source>(pub CstValue<'source>, pub CstMeta<'source>);
+
+impl<'source> CstToken<'source> {
+    pub const fn new (
+        source: &'source str, start: usize, length: usize, value: CstValue<'source>
+    ) -> Self {
+        Self(value, CstMeta { source, start, length })
+    }
+    pub const fn end (&self) -> usize {
+        self.1.start.saturating_add(self.1.length)
+    }
+    pub const fn slice (&'source self) -> &'source str {
+        self.slice_source(self.1.source)
+    }
+    pub const fn slice_source <'range> (&'source self, source: &'range str) -> &'range str {
+        str_range(source, self.1.start, self.end())
+    }
+    pub const fn slice_source_exp <'range> (&'source self, source: &'range str) -> &'range str {
+        str_range(source, self.1.start.saturating_add(1), self.end())
+    }
+    pub const fn with_value (self, value: CstValue<'source>) -> Self {
+        Self(value, self.1)
+    }
+    pub const fn value (&self) -> CstValue<'source> {
+        self.0
+    }
+    pub const fn error (self, error: DslError) -> Self {
+        Self(Value::Err(error), self.1)
+    }
+    pub const fn grow (self) -> Self {
+        Self(self.0, CstMeta { length: self.1.length.saturating_add(1), ..self.1 })
+    }
+    pub const fn grow_num (self, m: usize, c: char) -> Self {
+        use Value::*;
+        match to_digit(c) {
+            Result::Ok(n)  => Self(Num(10*m+n), self.grow().1),
+            Result::Err(e) => Self(Err(e), self.grow().1),
+        }
+    }
+    pub const fn grow_key (self) -> Self {
+        use Value::*;
+        let token = self.grow();
+        token.with_value(Key(token.slice_source(self.1.source)))
+    }
+    pub const fn grow_sym (self) -> Self {
+        use Value::*;
+        let token = self.grow();
+        token.with_value(Sym(token.slice_source(self.1.source)))
+    }
+    pub const fn grow_str (self) -> Self {
+        use Value::*;
+        let token = self.grow();
+        token.with_value(Str(token.slice_source(self.1.source)))
+    }
+    pub const fn grow_exp (self) -> Self {
+        use Value::*;
+        let token = self.grow();
+        if let Exp(depth, _) = token.value() {
+            token.with_value(Exp(depth, SourceIter::new(token.slice_source_exp(self.1.source))))
+        } else {
+            unreachable!()
+        }
+    }
+    pub const fn grow_in (self) -> Self {
+        let token = self.grow_exp();
+        if let Value::Exp(depth, source) = token.value() {
+            token.with_value(Value::Exp(depth.saturating_add(1), source))
+        } else {
+            unreachable!()
+        }
+    }
+    pub const fn grow_out (self) -> Self {
+        let token = self.grow_exp();
+        if let Value::Exp(depth, source) = token.value() {
+            if depth > 0 {
+                token.with_value(Value::Exp(depth - 1, source))
+            } else {
+                return self.error(Unexpected(')'))
+            }
+        } else {
+            unreachable!()
+        }
+    }
+}
+
+pub const fn to_number (digits: &str) -> DslResult<usize> {
+    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) -> DslResult<usize> {
+    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))
+    })
+}
+
+/// Static iteration helper.
+#[macro_export] macro_rules! iterate {
+    ($expr:expr => $arg: pat => $body:expr) => {
+        let mut iter = $expr;
+        while let Some(($arg, next)) = iter.next() {
+            $body;
+            iter = next;
+        }
+    }
+}
+
+pub const fn peek_src <'a> (source: &'a str) -> Option<CstToken<'a>> {
+    use Value::*;
+    let mut token: CstToken<'a> = CstToken::new(source, 0, 0, Nil);
+    iterate!(char_indices(source) => (start, c) => token = match token.value() {
+        Err(_) => return Some(token),
+        Nil => match c {
+            ' '|'\n'|'\r'|'\t' =>
+                token.grow(),
+            '(' =>
+                CstToken::new(source, start, 1, Exp(1, SourceIter::new(str_range(source, start, start + 1)))),
+            '"' =>
+                CstToken::new(source, start, 1, Str(str_range(source, start, start + 1))),
+            ':'|'@' =>
+                CstToken::new(source, start, 1, Sym(str_range(source, start, start + 1))),
+            '/'|'a'..='z' =>
+                CstToken::new(source, start, 1, Key(str_range(source, start, start + 1))),
+            '0'..='9' =>
+                CstToken::new(source, start, 1, match to_digit(c) {
+                    Ok(c) => Value::Num(c),
+                    Result::Err(e) => Value::Err(e)
+                }),
+            _ => token.error(Unexpected(c))
+        },
+        Str(_) => match c {
+            '"' => return Some(token),
+            _ => token.grow_str(),
+        },
+        Num(n) => match c {
+            '0'..='9' => token.grow_num(n, c),
+            ' '|'\n'|'\r'|'\t'|')' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Sym(_) => match c {
+            'a'..='z'|'A'..='Z'|'0'..='9'|'-' => token.grow_sym(),
+            ' '|'\n'|'\r'|'\t'|')' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Key(_) => match c {
+            'a'..='z'|'0'..='9'|'-'|'/' => token.grow_key(),
+            ' '|'\n'|'\r'|'\t'|')' => return Some(token),
+            _ => token.error(Unexpected(c))
+        },
+        Exp(depth, _) => match depth {
+            0 => return Some(token.grow_exp()),
+            _ => match c {
+                ')' => token.grow_out(),
+                '(' => token.grow_in(),
+                 _  => token.grow_exp(),
+            }
+        },
+    });
+    match token.value() {
+        Nil => None,
+        _ => Some(token),
+    }
+}