working llgrammar

src/double_enum.rs

@@ -13,7 +13,7 @@ macro_rules! double_enum {
                 ( $($args),+ )
             )?
         ),*}
-        #[derive(Debug, Clone, PartialEq)]
+        #[derive(Debug, Clone, PartialEq, Eq, Hash)]
         pub enum $bare_name {$($variant),*}
 
         impl PartialEq<$name> for $bare_name {

src/ll_grammar.rs

@@ -1,23 +1,231 @@
+use std::{
+    collections::{HashMap, HashSet},
+    fmt::Debug,
+    hash::Hash,
+};
+
 #[macro_export]
 macro_rules! ll_grammar {
     (
-        $tokens:ident,
+        $(
-        $bare_tokens:ident,
-        $grammar:ident,
-        $non_term:ident,
-        [$(
             $left:ident -> $(
                 $right:ident
             ),*
-        );* $(;)?]
+        );* $(;)?
-    ) => {};
+    ) => {
+        {
+            let mut map = HashMap::new();
+            $({
+                if !map.contains_key(&$left) {
+                    map.insert($left, Vec::new());
+                }
+                map.get_mut(&$left).unwrap().push(vec![$($right.into()),*]);
+            })*
+            $crate::ll_grammar::LLGrammar {
+                rules: map,
+                first: None,
+                follow: None,
+            }
+        }
+    };
 }
 
-enum Sentential<T, N> {
+#[derive(Debug, Clone)]
+pub enum Sentential<T, N> {
     Terminal(T),
     NoneTerminal(N),
 }
 
-pub struct Grammar<T, N> {
+pub struct LLGrammar<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash + Clone> {
-    rules: Vec<(T, Vec<Sentential<T, N>>)>,
+    pub rules: HashMap<N, Vec<Vec<Sentential<T, N>>>>,
+    /// none is epsilon
+    pub first: Option<HashMap<N, HashSet<Option<T>>>>,
+    /// none is $
+    pub follow: Option<HashMap<N, HashSet<Option<T>>>>,
+}
+
+impl<N: PartialEq + Eq + Hash + Clone + Debug, T: PartialEq + Eq + Hash + Clone + Debug>
+    LLGrammar<N, T>
+{
+    pub fn can_produce_epsilon(&self, rule: &Sentential<T, N>) -> bool {
+        match rule {
+            Sentential::Terminal(_) => false,
+            Sentential::NoneTerminal(nt) => self
+                .rules
+                .get(&nt)
+                .map(|f| f.iter().any(|v| v.is_empty()))
+                .unwrap_or(false),
+        }
+    }
+
+    pub fn gen_first(&mut self) {
+        let mut first: HashMap<N, HashSet<Option<T>>> = HashMap::new();
+        loop {
+            let mut change = false;
+            for (from, to) in self.rules.iter() {
+                'rule: for to in to.iter() {
+                    // for each rule from -> to = X -> Y1...Yk
+                    // add First(Yn) to First(X) if Y1...Yn-1 => e // n can be 1, disregarding the if
+                    // add e to First(X) if Y1...Yk => e
+                    for symbol in to {
+                        match symbol {
+                            Sentential::Terminal(a) => {
+                                first
+                                    .entry(from.clone())
+                                    .and_modify(|e| {
+                                        change |= e.insert(Some(a.clone()));
+                                    })
+                                    .or_insert_with(|| {
+                                        change = true;
+                                        HashSet::from([Some(a.clone())])
+                                    });
+                            }
+                            Sentential::NoneTerminal(nt) => {
+                                if let Some(set) = first.get(nt).cloned() {
+                                    first
+                                        .entry(from.clone())
+                                        .and_modify(|e| {
+                                            for val in set.iter() {
+                                                change |= e.insert(val.clone());
+                                            }
+                                        })
+                                        .or_insert_with(|| {
+                                            change = true;
+                                            set
+                                        });
+                                }
+                            }
+                        }
+                        if !self.can_produce_epsilon(symbol) {
+                            continue 'rule;
+                        }
+                    }
+                    first
+                        .entry(from.clone())
+                        .and_modify(|e| {
+                            change |= e.insert(None);
+                        })
+                        .or_insert_with(|| {
+                            change = true;
+                            HashSet::from([None])
+                        });
+                }
+            }
+            if !change {
+                break;
+            }
+        }
+
+        self.first = Some(first);
+    }
+
+    pub fn first(&self, sent: &Vec<Sentential<T, N>>) -> HashSet<Option<T>> {
+        assert!(self.first.is_some(), "Please call gen_first before this!");
+        let mut out = HashSet::<Option<T>>::new();
+
+        // Y1Y2...Yk = al
+        // add First(Yn) to First(al) if Y1...Yn-1 => e // n can be 1, disregarding the if
+        // add e to First(al) if Y1...Yk => e
+        'rule: {
+            for symbol in sent {
+                match symbol {
+                    Sentential::Terminal(a) => {
+                        out.insert(Some(a.clone()));
+                    }
+                    Sentential::NoneTerminal(nt) => {
+                        if let Some(set) = self.first.as_ref().unwrap().get(nt).cloned() {
+                            out.extend(set);
+                        }
+                    }
+                }
+                if !self.can_produce_epsilon(symbol) {
+                    break 'rule;
+                }
+            }
+            out.insert(None);
+        }
+        out
+    }
+
+    pub fn gen_follow(&mut self, start: N) {
+        if self.first == None {
+            self.gen_first();
+        }
+        let mut follow: HashMap<N, HashSet<Option<T>>> = HashMap::new();
+        follow.insert(start, HashSet::from([None]));
+        loop {
+            let mut change = false;
+
+            for (from, to) in self.rules.iter() {
+                for to in to.iter() {
+                    // a
+                    // if A -> aBb then add First(b) - {e} to Follow(B)
+                    // and if A -> aBb and e in First(b) add Follow(A) to Follow(B)
+                    if to.len() >= 2 {
+                        for i in 0..(to.len() - 1) {
+                            let slice = to[i + 1..].iter().map(|f| f.clone()).collect::<Vec<_>>();
+                            match to.get(i) {
+                                Some(Sentential::NoneTerminal(b)) => {
+                                    let mut set = self.first(&slice);
+                                    if set.contains(&None) {
+                                        if let Some(set) = follow.get(from).cloned() {
+                                            follow
+                                                .entry(b.clone())
+                                                .and_modify(|e| {
+                                                    for val in set.iter() {
+                                                        change |= e.insert(val.clone());
+                                                    }
+                                                })
+                                                .or_insert_with(|| {
+                                                    change = true;
+                                                    set
+                                                });
+                                        }
+                                    }
+                                    set.remove(&None);
+                                    follow
+                                        .entry(b.clone())
+                                        .and_modify(|e| {
+                                            for val in set.iter() {
+                                                change |= e.insert(val.clone());
+                                            }
+                                        })
+                                        .or_insert_with(|| {
+                                            change = true;
+                                            set
+                                        });
+                                }
+                                _ => (),
+                            }
+                        }
+                    }
+                    // b
+                    // and if A -> aB add Follow(A) to Follow(B)
+                    match to.last() {
+                        Some(Sentential::NoneTerminal(b)) => {
+                            if let Some(set) = follow.get(from).cloned() {
+                                follow
+                                    .entry(b.clone())
+                                    .and_modify(|e| {
+                                        for val in set.iter() {
+                                            change |= e.insert(val.clone());
+                                        }
+                                    })
+                                    .or_insert_with(|| {
+                                        change = true;
+                                        set
+                                    });
+                            }
+                        }
+                        _ => (),
+                    }
+                }
+            }
+
+            if !change {
+                break;
+            }
+        }
+        self.follow = Some(follow);
+    }
 }

src/main.rs

@@ -1,12 +1,12 @@
+mod double_enum;
 mod ll_grammar;
 mod scanner;
-mod double_enum;
+use ll_grammar::{LLGrammar, Sentential};
 use regex::{Match, Regex};
 use scanner::Scanner;
+use std::collections::HashMap;
 
-
+double_enum!(
-
-scanner!(
     BareTokens, Tokens {
         WhiteSpace,
         Add,
@@ -14,11 +14,17 @@ scanner!(
         Mul,
         Div,
         While,
+        LBrace,
+        RBrace,
         Ident(String),
         Int(i64),
         Float(f64),
     }
-    r"^\s|\t|\n" : |_,_|{
+);
+
+scanner!(
+    Tokens,
+    r"^\s|\t|\n" : |_,_| {
         Some(WhiteSpace)
     }
     r"^\+" : |_,_| {
@@ -36,6 +42,12 @@ scanner!(
     r"^while" : |_,_| {
         Some(While)
     }
+    r"\(" : |_,_| {
+        Some(LBrace)
+    }
+    r"\)" : |_,_| {
+        Some(RBrace)
+    }
     r"^[a-zA-Z](\w)*" : |_, m: Match<'_>| {
         Some(Ident(String::from(m.as_str())))
     }
@@ -47,28 +59,47 @@ scanner!(
     }
 );
 
+#[derive(Debug, PartialEq, Eq, Hash, Clone)]
 enum NoneTerminals {
     P,
     E,
     Ei,
     T,
+    Ti,
+    F,
 }
 
-ll_grammar!(
+impl<T> From<NoneTerminals> for Sentential<T, NoneTerminals> {
-    Tokens,
+    fn from(value: NoneTerminals) -> Self {
-    BareTokens,
+        Sentential::NoneTerminal(value)
-    Grammar,
+    }
-    NoneTerminals,
+}
-    [
+
+impl<N> From<BareTokens> for Sentential<BareTokens, N> {
+    fn from(value: BareTokens) -> Self {
+        Sentential::Terminal(value)
+    }
+}
+
+fn grammer() -> LLGrammar<NoneTerminals, BareTokens> {
+    use BareTokens::*;
+    use NoneTerminals::*;
+    ll_grammar![
         P -> E;
         E -> T,Ei;
         Ei -> Add,T,Ei;
+        Ei -> Sub,T,Ei;
         Ei -> ;
-        T -> Ident;
+        T -> F,Ti;
-        T -> Int;
+        Ti -> Mul,F,Ti;
+        Ti -> Div,F,Ti;
+        Ti -> ;
+        F -> LBrace, E, RBrace;
+        F -> Int;
+        F -> Float;
+        F -> Ident;
     ]
-);
+}
-
 fn main() {
     let code = String::from("while 12 + a - 3.4 / 0. * 4");
     let mut m = Scanner::<Tokens>::new(code).with_skipping(Tokens::WhiteSpace);
@@ -78,25 +109,9 @@ fn main() {
     if !m.is_empty() {
         println!("Error");
     }
-}
 
-#[derive(Debug, Clone, PartialEq)]
+    let mut grammar = grammer();
-pub enum Test {
+    grammar.gen_follow(NoneTerminals::P);
-    A,
+    println!("first: {:?}", grammar.first);
-    B,
+    println!("follow: {:?}", grammar.follow);
-}
-#[derive(Debug, Clone)]
-pub enum BareTest {
-    A,
-    B,
-}
-
-impl PartialEq<Test> for BareTest {
-    fn eq(&self, other: &Test) -> bool {
-        match (self, other){
-            (BareTest::A, Test::A) => true,
-            (BareTest::B, Test::B)=> true,
-            _=> false
-        }
-    }
 }

src/scanner.rs

@@ -2,40 +2,9 @@ use std::marker::PhantomData;
 
 #[macro_export]
 macro_rules! scanner {
-    ($bare_name:ident, $name:ident {
+    ($name:ident,$(
-        $(
-            $variant:ident$(
-                ( $($args:ty),+ $(,)? )
-            )?
-        ),* $(,)?
-    }
-    $(
        $regex:tt : $code:expr
     )*) => {
-        #[derive(Debug, Clone, PartialEq)]
-        pub enum $name {$(
-            $variant$(
-                ( $($args),+ )
-            )?
-        ),*}
-        #[derive(Debug, Clone, PartialEq)]
-        pub enum $bare_name {$($variant),*}
-
-        impl PartialEq<$name> for $bare_name {
-            fn eq(&self, other: &$name) -> bool {
-                match (self, other){
-                    $(($bare_name::$variant, $name::$variant{ .. }) => true,)*
-                    _=> false
-                }
-            }
-        }
-        
-        impl PartialEq<$bare_name> for $name {
-            fn eq(&self, other: &$bare_name) -> bool {
-                other.eq(self)
-            }
-        }
-
         impl $crate::scanner::MatchNext<$name> for $name {
             fn match_next(code: &String) -> Option<(Self, usize)> {
                 use $name::*;