slr parse table

src/bin/book.rs

@@ -78,4 +78,7 @@ fn main() {
     println!("follow: {:?}", grammar.follow);
     grammar.gen_lr0_automaton();
     println!("automaton: {:?}", grammar.lr0_automaton);
+    grammar.gen_slr_parse_table();
+    println!("parse_table: {:?}", grammar.slr_parse_table);
+
 }

src/cfg/ll_grammar.rs

@@ -4,6 +4,9 @@ use super::{Grammar, Sentential};
 
 impl<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash + Clone> Grammar<N, T> {
     pub fn gen_ll_parse_table(&mut self) -> bool {
+        if self.first.is_none() {
+            self.gen_first();
+        }
         if self.follow.is_none() {
             self.gen_follow();
         }
@@ -11,6 +14,9 @@ impl<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash + Clone> Grammar
             return false;
         }
         let mut conflict = false;
+        // left derivation
+        // when hidding N and T is next (None = e)
+        // then the n'th (usize) variant of N can be used.
         let mut parse_table: HashMap<(N, Option<T>), usize> = HashMap::new();
         for (from, to) in self.rules.iter() {
             for (id, to) in to.iter().enumerate() {

src/cfg/lr0.rs

@@ -4,64 +4,80 @@ use std::{
     rc::{Rc, Weak},
 };
 
-use super::{Grammar, Sentential};
+use super::{Grammar, RuleIndex, Sentential};
 
 pub type RL0Automaton<N, T> =
-    HashMap<Rc<LR0State<N, T>>, Vec<(Sentential<N, T>, Weak<LR0State<N, T>>)>>;
+    HashMap<Rc<LR0State<N>>, HashMap<Sentential<N, T>, Weak<LR0State<N>>>>;
-
-pub type RL0Rule<N, T> = (N, Vec<Sentential<N, T>>, usize);
 
 #[derive(Debug, Eq, PartialEq)]
-pub struct LR0State<N: Hash + Eq, T: Hash + Eq>(HashSet<RL0Rule<N, T>>);
+pub struct LR0State<N: Hash + Eq>(HashSet<(RuleIndex<N>, usize)>);
 
-impl<N: Hash + Eq + Clone, T: Hash + Eq + Clone> LR0State<N, T> {
+impl<N: Hash + Eq + Ord> Hash for LR0State<N> {
-    pub fn next_kernel(&self, read: &Sentential<N, T>) -> Self {
-        let mut next_state: LR0State<N, T> = LR0State(HashSet::new());
-        for (from, to, dot) in self.0.iter() {
-            if to.get(*dot).map(|elem| *elem == *read).unwrap_or(false) {
-                next_state.0.insert((from.clone(), to.clone(), dot + 1));
-            }
-        }
-        next_state
-    }
-    pub fn readable(&self) -> HashSet<Sentential<N, T>> {
-        let mut readbles = HashSet::new();
-        for (_, to, dot) in self.0.iter() {
-            if let Some(l) = to.get(*dot) {
-                readbles.insert(l.clone());
-            }
-        }
-        readbles
-    }
-}
-impl<N: Hash + Eq + Ord, T: Hash + Eq + Ord> Hash for LR0State<N, T> {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        let mut a: Vec<&RL0Rule<N, T>> = self.0.iter().collect();
+        let mut a: Vec<&(RuleIndex<N>, usize)> = self.0.iter().collect();
         a.sort();
         for s in a.iter() {
             s.hash(state);
         }
     }
 }
+#[derive(Debug)]
+pub enum SlrAction<Shift, Reduce> {
+    Shift(Shift),
+    Reduce(Reduce),
+}
+
+pub type SlrActionTable<N, T> = HashMap<(usize, Option<T>), SlrAction<usize, RuleIndex<N>>>;
+pub type SlrGotoTable<N> = HashMap<(usize, N), usize>;
+pub type SlrParseTable<N, T> = (SlrActionTable<N, T>, SlrGotoTable<N>);
 
 impl<N, T> Grammar<N, T>
 where
     N: PartialEq + Eq + Hash + Clone + Ord,
     T: PartialEq + Eq + Hash + Clone + Ord,
 {
-    pub fn lr0_clozure(&self, mut state: LR0State<N, T>) -> LR0State<N, T> {
+    pub fn next_kernel(&self, state: &LR0State<N>, read: &Sentential<N, T>) -> LR0State<N> {
+        let mut next_state: LR0State<N> = LR0State(HashSet::new());
+        for ((from, rule_id), dot) in state.0.iter() {
+            let Some(to) = self.rules.get(from).and_then(|v| v.get(*rule_id)) else {
+                continue;
+            };
+            if to.get(*dot).map(|elem| *elem == *read).unwrap_or(false) {
+                next_state.0.insert(((from.clone(), *rule_id), dot + 1));
+            }
+        }
+        next_state
+    }
+    pub fn readable(&self, state: &LR0State<N>) -> HashSet<Sentential<N, T>> {
+        let mut readables = HashSet::new();
+        for ((from, rule_id), dot) in state.0.iter() {
+            let Some(to) = self.rules.get(from).and_then(|v| v.get(*rule_id)) else {
+                continue;
+            };
+            if let Some(l) = to.get(*dot) {
+                readables.insert(l.clone());
+            }
+        }
+        readables
+    }
+    pub fn lr0_clozure(&self, mut state: LR0State<N>) -> LR0State<N> {
         loop {
             let mut change = false;
             let nt = state
                 .0
                 .iter()
-                .filter_map(|(_, to, dot)| to.get(*dot).cloned())
+                .filter_map(|((from, rule_id), dot)| {
+                    self.rules
+                        .get(from)
+                        .and_then(|v| v.get(*rule_id))
+                        .and_then(|to| to.get(*dot).cloned())
+                })
                 .collect::<Vec<_>>();
             for n in nt {
                 if let Sentential::NoneTerminal(n) = n {
                     if let Some(rule) = self.rules.get(&n) {
-                        for to in rule {
+                        for to in 0..rule.len() {
-                            change |= state.0.insert((n.clone(), to.clone(), 0));
+                            change |= state.0.insert(((n.clone(), to), 0));
                         }
                     }
                 }
@@ -75,34 +91,101 @@ where
 
     pub fn gen_lr0_automaton(&mut self) {
         let mut out: RL0Automaton<N, T> = HashMap::new();
+        // add state zero
         let mut start_state = LR0State(HashSet::new());
         if let Some(rule) = self.rules.get(&self.start) {
-            for to in rule {
+            for to in 0..rule.len() {
-                start_state.0.insert((self.start.clone(), to.clone(), 0));
+                start_state.0.insert(((self.start.clone(), to), 0));
             }
         }
+        // add state to graph and mark for todo
         let rc = Rc::new(self.lr0_clozure(start_state));
         let mut todo = vec![Rc::downgrade(&rc)];
-        out.insert(rc, Vec::new());
+        out.insert(rc, HashMap::new());
-        while let Some(elem) = todo.pop() {
+
-            if let Some(elem) = elem.upgrade() {
+        // add states while marked states exists
+        while let Some(state) = todo.pop() {
+            if let Some(state) = state.upgrade() {
+                // new adjacent list
                 let mut vec = Vec::new();
-                for none_terminal in elem.readable() {
+
-                    let next_state = self.lr0_clozure(elem.next_kernel(&none_terminal));
+                // add clozures from the kernels from all readable symbols
+                for none_terminal in self.readable(&state) {
+                    let next_state = self.lr0_clozure(self.next_kernel(&state, &none_terminal));
                     let rc = Rc::new(next_state);
                     if let Some((k, _)) = out.get_key_value(&rc) {
                         vec.push((none_terminal, Rc::downgrade(k)));
                     } else {
                         todo.push(Rc::downgrade(&rc));
                         vec.push((none_terminal, Rc::downgrade(&rc)));
-                        out.insert(rc, Vec::new());
+                        out.insert(rc, HashMap::new());
                     }
                 }
-                out.entry(elem).and_modify(|elem| {
+                // write adjacent list to state
+                // does not check duplicates. Is not needed, because `readable` returns a set
+                out.entry(state).and_modify(|elem| {
                     elem.extend(vec);
                 });
             }
         }
         self.lr0_automaton = Some(out);
     }
+
+    pub fn gen_slr_parse_table(&mut self) {
+        if self.follow.is_none() {
+            self.gen_follow();
+        }
+        if self.lr0_automaton.is_none() {
+            self.gen_lr0_automaton();
+        }
+
+        let lr0_automaton = self.lr0_automaton.as_ref().unwrap();
+
+        let ids: HashMap<Rc<LR0State<N>>, usize> = HashMap::from_iter(
+            lr0_automaton
+                .iter()
+                .enumerate()
+                .map(|(id, (a, _))| (a.clone(), id)),
+        );
+
+        // none is $
+        let mut action: SlrActionTable<N, T> = HashMap::new();
+        let mut goto: SlrGotoTable<N> = HashMap::new();
+        for (state, to) in lr0_automaton {
+            let id = ids
+                .get(state)
+                .expect("Found broken state in slr parse table gen.");
+
+            for go in self.readable(state) {
+                let Some(to) = to.get(&go).and_then(|to| to.upgrade()) else {
+                    continue;
+                };
+
+                let to_id = ids
+                    .get(&to)
+                    .expect("Found broken state in slr parse table gen.");
+
+                match go {
+                    Sentential::Terminal(t) => {
+                        action.insert((*id, Some(t)), SlrAction::Shift(*to_id));
+                    }
+                    Sentential::NoneTerminal(nt) => {
+                        goto.insert((*id, nt), *to_id);
+                    }
+                };
+            }
+
+            for ((from, rule_id), dot) in state.0.iter() {
+                let Some(to) = self.rules.get(from).and_then(|v| v.get(*rule_id)) else {
+                    continue;
+                };
+                if to.len() <= *dot {
+                    for follow in self.follow(from) {
+                        action.insert((*id, follow), SlrAction::Reduce((from.clone(), *rule_id)));
+                    }
+                }
+            }
+        }
+        self.slr_parse_table = Some((action, goto));
+    }
 }

src/cfg/mod.rs

@@ -3,7 +3,7 @@ use std::{
     hash::Hash,
 };
 
-use lr0::RL0Automaton;
+use lr0::{RL0Automaton, SlrParseTable};
 
 pub mod ll_grammar;
 pub mod lr0;
@@ -33,6 +33,7 @@ macro_rules! cfg_grammar {
                 follow: None,
                 ll_parse_table: None,
                 lr0_automaton: None,
+                slr_parse_table: None,   
             }
         }
     };
@@ -66,6 +67,8 @@ impl<T: Ord, N: Ord> Ord for Sentential<N, T> {
     }
 }
 
+pub type RuleIndex<N> = (N, usize);
+
 pub struct Grammar<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash + Clone> {
     pub start: N,
     pub rules: HashMap<N, Vec<Vec<Sentential<N, T>>>>,
@@ -83,6 +86,9 @@ pub struct Grammar<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash +
     /// - key: states
     /// - value: list with read symbol and linked node.
     pub lr0_automaton: Option<RL0Automaton<N, T>>,
+
+    ///
+    pub slr_parse_table: Option<SlrParseTable<N, T>>,
 }
 
 impl<N: PartialEq + Eq + Hash + Clone, T: PartialEq + Eq + Hash + Clone> Grammar<N, T> {