lr1 construction seems to be working, tests are not yet really stable

src/grammar/repr.rs

@@ -5,9 +5,8 @@
  */
 
 use intern::InternedString;
-use std::collections::HashMap;
 use std::fmt::{Debug, Display, Formatter, Error};
-use util::Sep;
+use util::{map, Map, Sep};
 
 // These concepts we re-use wholesale
 pub use grammar::parse_tree::{NonterminalString, Span, TerminalString};
@@ -15,8 +14,8 @@ pub use grammar::parse_tree::{NonterminalString, Span, TerminalString};
 #[derive(Clone, Debug)]
 pub struct Grammar {
     pub action_fn_defns: Vec<ActionFnDefn>,
-    pub productions: HashMap<NonterminalString, Vec<Production>>,
-    pub conversions: HashMap<TerminalString, TerminalString>,
+    pub productions: Map<NonterminalString, Vec<Production>>,
+    pub conversions: Map<TerminalString, TerminalString>,
     pub types: Types,
 }
 
@@ -54,13 +53,13 @@ pub enum TypeRepr {
 #[derive(Clone, Debug)]
 pub struct Types {
     terminal_type: TypeRepr,
-    nonterminal_types: HashMap<NonterminalString, TypeRepr>
+    nonterminal_types: Map<NonterminalString, TypeRepr>
 }
 
 impl Types {
     pub fn new(terminal_type: TypeRepr) -> Types {
         Types { terminal_type: terminal_type,
-                nonterminal_types: HashMap::new() }
+                nonterminal_types: map() }
     }
 
     pub fn add_type(&mut self, nt_id: NonterminalString, ty: TypeRepr) {
@@ -173,7 +172,7 @@ impl Grammar {
                types: Types)
                -> Grammar
     {
-        let mut productions = HashMap::new();
+        let mut productions = map();
 
         for production in flat_productions {
             let mut vec = productions.entry(production.nonterminal).or_insert(vec![]);

src/intern/mod.rs

@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::cell::RefCell;
 use std::fmt::{Debug, Display, Error, Formatter};
 use std::cmp::{PartialOrd, Ord, Ordering};
+use util::{map, Map};
 
 #[cfg(test)]
 mod test;
@@ -50,7 +51,7 @@ fn write<F,R>(f: F) -> R
 
 impl Interner {
     fn new() -> Interner {
-        Interner { map: HashMap::new(), strings: vec![] }
+        Interner { map: map(), strings: vec![] }
     }
 
     pub fn data(&self, i: InternedString) -> &str {

src/lr1/first/mod.rs

@@ -2,6 +2,7 @@
 
 use grammar::repr::*;
 use std::collections::{HashMap, HashSet};
+use util::{map, Map};
 
 use super::Lookahead;
 
@@ -16,7 +17,7 @@ pub type FirstSet = HashSet<Option<TerminalString>>;
 
 impl FirstSets {
     pub fn new(grammar: &Grammar) -> FirstSets {
-        let mut this = FirstSets { map: HashMap::new() };
+        let mut this = FirstSets { map: map() };
         let mut changed = true;
         while changed {
             changed = false;

src/lr1/mod.rs

@@ -4,7 +4,7 @@ use grammar::repr::*;
 use std::collections::{HashMap, HashSet};
 use std::fmt::{Debug, Formatter, Error};
 use std::rc::Rc;
-use util::Prefix;
+use util::{map, Map, Multimap, Set, Prefix};
 
 mod first;
 
@@ -15,15 +15,16 @@ struct LR1<'grammar> {
     first_sets: first::FirstSets,
 }
 
+#[derive(Debug)]
 struct State<'grammar> {
-    configurations: Configurations<'grammar>,
-    shifts: HashMap<TerminalString, StateIndex>,
-    gotos: HashMap<NonterminalString, StateIndex>,
+    items: Items<'grammar>,
+    shifts: Vec<(TerminalString, StateIndex)>,
+    gotos: Vec<(NonterminalString, StateIndex)>,
 }
 
-type Configurations<'grammar> = Rc<Vec<Configuration<'grammar>>>;
+type Items<'grammar> = Rc<Vec<Item<'grammar>>>;
 
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
 struct StateIndex(usize);
 
 #[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
@@ -33,7 +34,7 @@ enum Lookahead {
 }
 
 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
-struct Configuration<'grammar> {
+struct Item<'grammar> {
     production: &'grammar Production,
     index: usize, // the dot comes before `index`, so `index` would be 1 for X = A (*) B C
     lookahead: Lookahead,
@@ -41,7 +42,7 @@ struct Configuration<'grammar> {
 
 struct StateSet<'grammar> {
     states: Vec<State<'grammar>>,
-    state_map: HashMap<Configurations<'grammar>, StateIndex>,
+    state_map: Map<Items<'grammar>, StateIndex>,
 }
 
 impl<'grammar> LR1<'grammar> {
@@ -52,30 +53,38 @@ impl<'grammar> LR1<'grammar> {
         }
     }
 
-    fn build_states(&mut self, start_nt: NonterminalString) -> Vec<State<'grammar>> {
+    fn build_states(&self, start_nt: NonterminalString) -> Vec<State<'grammar>> {
         let mut state_set = StateSet::new();
 
         // create the starting state
         state_set.add_state(
             self.transitive_closure(
-                self.configurations(start_nt, 0, Lookahead::EOF)));
+                self.items(start_nt, 0, Lookahead::EOF)));
 
         let mut counter = 0;
         while counter < state_set.states.len() {
-            let configurations = state_set.states[counter].configurations.clone();
-            counter += 1;
+            let items = state_set.states[counter].items.clone();
 
-            // for each configuration where we can shift, do so, and
-            // create the transitive closure of the resulting state
-            let shifted_configurations =
-                configurations
-                .iter()
-                .filter_map(|configuration| configuration.shifted_configuration())
-                .map(|configuration| self.transitive_closure(vec![configuration]));
+            // group the items that we can transition into by shifting
+            // over a term or nonterm
+            let transitions: Multimap<Symbol, Item<'grammar>> =
+                items.iter()
+                     .filter_map(|item| item.shifted_item())
+                     .collect();
 
-            // add a state for each of those cases where we did a shift
-            for configuration in shifted_configurations {
-                state_set.add_state(configuration);
+            for (symbol, items) in transitions.into_iter() {
+                let items = self.transitive_closure(items);
+                let next_state = state_set.add_state(items);
+
+                // FIXME check for conflicts
+                match symbol {
+                    Symbol::Terminal(t) => {
+                        state_set.states[counter].shifts.push((t, next_state));
+                    }
+                    Symbol::Nonterminal(t) => {
+                        state_set.states[counter].gotos.push((t, next_state));
+                    }
+                }
             }
 
             // extract a new state
@@ -85,17 +94,17 @@ impl<'grammar> LR1<'grammar> {
         state_set.states
     }
 
-    fn configurations(&self,
+    fn items(&self,
                       id: NonterminalString,
                       index: usize,
                       lookahead: Lookahead)
-                      -> Vec<Configuration<'grammar>>
+                      -> Vec<Item<'grammar>>
     {
         self.grammar.productions_for(id)
                     .iter()
                     .map(|production| {
                         debug_assert!(index <= production.symbols.len());
-                        Configuration { production: production,
+                        Item { production: production,
                                         index: index,
                                         lookahead: lookahead }
                     })
@@ -103,45 +112,45 @@ impl<'grammar> LR1<'grammar> {
     }
 
     // expands `state` with epsilon moves
-    fn transitive_closure(&self, mut configurations: Vec<Configuration<'grammar>>)
-                          -> Configurations<'grammar>
+    fn transitive_closure(&self, mut items: Vec<Item<'grammar>>)
+                          -> Items<'grammar>
     {
         let mut counter = 0;
 
-        let mut set: HashSet<Configuration<'grammar>> =
-            configurations.iter().cloned().collect();
+        let mut set: Set<Item<'grammar>> =
+            items.iter().cloned().collect();
 
-        while counter < configurations.len() {
-            let new_configurations: Vec<_> =
-                configurations[counter..]
+        while counter < items.len() {
+            let new_items: Vec<_> =
+                items[counter..]
                 .iter()
-                .filter_map(|configuration| {
-                    let shift_symbol = configuration.shift_symbol();
+                .filter_map(|item| {
+                    let shift_symbol = item.shift_symbol();
                     match shift_symbol {
                         None => None, // requires a reduce
                         Some((Symbol::Terminal(_), _)) => None, // requires a shift
                         Some((Symbol::Nonterminal(nt), remainder)) => {
-                            Some((nt, remainder, configuration.lookahead))
+                            Some((nt, remainder, item.lookahead))
                         }
                     }
                 })
                 .flat_map(|(nt, remainder, lookahead)| {
                     let first_set = self.first_sets.first(remainder, lookahead);
                     first_set.into_iter()
-                             .flat_map(move |l| self.configurations(nt, 0, l))
+                             .flat_map(move |l| self.items(nt, 0, l))
                 })
-                .filter(|&configuration| set.insert(configuration))
+                .filter(|&item| set.insert(item))
                 .collect();
 
-            counter = configurations.len();
-            configurations.extend(new_configurations);
+            counter = items.len();
+            items.extend(new_items);
         }
 
-        Rc::new(configurations)
+        Rc::new(items)
     }
 }
 
-impl<'grammar> Configuration<'grammar> {
+impl<'grammar> Item<'grammar> {
     fn can_shift(&self) -> bool {
         self.index < self.production.symbols.len()
     }
@@ -150,11 +159,12 @@ impl<'grammar> Configuration<'grammar> {
         self.index == self.production.symbols.len()
     }
 
-    fn shifted_configuration(&self) -> Option<Configuration<'grammar>> {
+    fn shifted_item(&self) -> Option<(Symbol, Item<'grammar>)> {
         if self.can_shift() {
-            Some(Configuration { production: self.production,
-                                 index: self.index + 1,
-                                 lookahead: self.lookahead })
+            Some((self.production.symbols[self.index],
+                  Item { production: self.production,
+                                  index: self.index + 1,
+                                  lookahead: self.lookahead }))
         } else {
             None
         }
@@ -173,23 +183,23 @@ impl<'grammar> StateSet<'grammar> {
     fn new() -> StateSet<'grammar> {
         StateSet {
             states: vec![],
-            state_map: HashMap::new(),
+            state_map: map(),
         }
     }
 
-    fn add_state(&mut self, configurations: Configurations<'grammar>) -> StateIndex {
+    fn add_state(&mut self, items: Items<'grammar>) -> StateIndex {
         let states = &mut self.states;
-        *self.state_map.entry(configurations.clone()).or_insert_with(|| {
+        *self.state_map.entry(items.clone()).or_insert_with(|| {
             let index = StateIndex(states.len());
-            states.push(State { configurations: configurations,
-                                     shifts: HashMap::new(),
-                                     gotos: HashMap::new() });
+            states.push(State { items: items,
+                                shifts: Vec::new(),
+                                gotos: Vec::new() });
             index
         })
     }
 }
 
-impl<'grammar> Debug for Configuration<'grammar> {
+impl<'grammar> Debug for Item<'grammar> {
     fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
         write!(fmt, "{} ={} (*){} [{:?}]",
                self.production.nonterminal,
@@ -207,3 +217,9 @@ impl Debug for Lookahead {
         }
     }
 }
+
+impl Debug for StateIndex {
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
+        write!(fmt, "S{}", self.0)
+    }
+}

src/lr1/test.rs

@@ -1,21 +1,21 @@
 use intern::intern;
 use grammar::repr::*;
 use test_util::{expect_debug, normalized_grammar};
-use super::{Configuration, Configurations, Lookahead, LR1};
+use super::{Items, Lookahead, LR1};
 use super::Lookahead::EOF;
 
 fn nt(t: &str) -> NonterminalString {
     NonterminalString(intern(t))
 }
 
-fn configurations<'g>(grammar: &'g Grammar, nonterminal: &str, index: usize, la: Lookahead)
-                      -> Configurations<'g>
+fn items<'g>(grammar: &'g Grammar, nonterminal: &str, index: usize, la: Lookahead)
+                      -> Items<'g>
 {
     let lr1 = LR1::new(&grammar);
-    let configurations =
+    let items =
         lr1.transitive_closure(
-            lr1.configurations(nt(nonterminal), index, la));
-    configurations
+            lr1.items(nt(nonterminal), index, la));
+    items
 }
 
 #[test]
@@ -30,8 +30,8 @@ grammar Foo {
     };
 }
 "#);
-    let configurations = configurations(&grammar, "A", 0, EOF);
-    expect_debug(configurations, r#"[
+    let items = items(&grammar, "A", 0, EOF);
+    expect_debug(items, r#"[
     A = (*) B "C" [EOF],
     B = (*) "D" ["C"],
     B = (*) ["C"]
@@ -55,7 +55,7 @@ grammar Foo {
 }
 "#);
 
-    expect_debug(configurations(&grammar, "A", 0, EOF), r#"[
+    expect_debug(items(&grammar, "A", 0, EOF), r#"[
     A = (*) B C [EOF],
     B = (*) "B1" ["C1"],
     B = (*) ["C1"],
@@ -63,9 +63,241 @@ grammar Foo {
     B = (*) [EOF]
 ]"#);
 
-    expect_debug(configurations(&grammar, "A", 1, EOF), r#"[
+    expect_debug(items(&grammar, "A", 1, EOF), r#"[
     A = B (*) C [EOF],
     C = (*) "C1" [EOF],
     C = (*) [EOF]
 ]"#);
 }
+
+#[test]
+fn expr_grammar1() {
+    let grammar = normalized_grammar(r#"
+grammar Foo {
+    token Tok where { };
+
+    S: () =
+        E => ();
+
+    E: () = {
+        E "-" T => ();
+        T => ();
+    };
+
+    T: () = {
+        "N" => ();
+        "(" E ")" => ();
+    };
+}
+"#);
+
+    let lr1 = LR1::new(&grammar);
+    let mut states = lr1.build_states(nt("S"));
+    for state in &mut states {
+        state.shifts.sort();
+        state.gotos.sort();
+    }
+    expect_debug(&states, r#"[
+    State {
+        items: [
+            S = (*) E [EOF],
+            E = (*) E "-" T [EOF],
+            E = (*) T [EOF],
+            E = (*) E "-" T ["-"],
+            E = (*) T ["-"],
+            T = (*) "N" [EOF],
+            T = (*) "(" E ")" [EOF],
+            T = (*) "N" ["-"],
+            T = (*) "(" E ")" ["-"]
+        ],
+        shifts: [
+            ("(", S4),
+            ("N", S3)
+        ],
+        gotos: [
+            (E, S2),
+            (T, S1)
+        ]
+    },
+    State {
+        items: [
+            E = T (*) [EOF],
+            E = T (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            S = E (*) [EOF],
+            E = E (*) "-" T [EOF],
+            E = E (*) "-" T ["-"]
+        ],
+        shifts: [
+            ("-", S5)
+        ],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "N" (*) [EOF],
+            T = "N" (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "(" (*) E ")" [EOF],
+            T = "(" (*) E ")" ["-"],
+            E = (*) E "-" T [")"],
+            E = (*) T [")"],
+            E = (*) E "-" T ["-"],
+            E = (*) T ["-"],
+            T = (*) "N" [")"],
+            T = (*) "(" E ")" [")"],
+            T = (*) "N" ["-"],
+            T = (*) "(" E ")" ["-"]
+        ],
+        shifts: [
+            ("(", S8),
+            ("N", S9)
+        ],
+        gotos: [
+            (E, S7),
+            (T, S6)
+        ]
+    },
+    State {
+        items: [
+            E = E "-" (*) T [EOF],
+            E = E "-" (*) T ["-"],
+            T = (*) "N" [EOF],
+            T = (*) "(" E ")" [EOF],
+            T = (*) "N" ["-"],
+            T = (*) "(" E ")" ["-"]
+        ],
+        shifts: [
+            ("(", S4),
+            ("N", S3)
+        ],
+        gotos: [
+            (T, S10)
+        ]
+    },
+    State {
+        items: [
+            E = T (*) [")"],
+            E = T (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "(" E (*) ")" [EOF],
+            T = "(" E (*) ")" ["-"],
+            E = E (*) "-" T [")"],
+            E = E (*) "-" T ["-"]
+        ],
+        shifts: [
+            (")", S12),
+            ("-", S11)
+        ],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "(" (*) E ")" [")"],
+            T = "(" (*) E ")" ["-"],
+            E = (*) E "-" T [")"],
+            E = (*) T [")"],
+            E = (*) E "-" T ["-"],
+            E = (*) T ["-"],
+            T = (*) "N" [")"],
+            T = (*) "(" E ")" [")"],
+            T = (*) "N" ["-"],
+            T = (*) "(" E ")" ["-"]
+        ],
+        shifts: [
+            ("(", S8),
+            ("N", S9)
+        ],
+        gotos: [
+            (E, S13),
+            (T, S6)
+        ]
+    },
+    State {
+        items: [
+            T = "N" (*) [")"],
+            T = "N" (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            E = E "-" T (*) [EOF],
+            E = E "-" T (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            E = E "-" (*) T [")"],
+            E = E "-" (*) T ["-"],
+            T = (*) "N" [")"],
+            T = (*) "(" E ")" [")"],
+            T = (*) "N" ["-"],
+            T = (*) "(" E ")" ["-"]
+        ],
+        shifts: [
+            ("(", S8),
+            ("N", S9)
+        ],
+        gotos: [
+            (T, S14)
+        ]
+    },
+    State {
+        items: [
+            T = "(" E ")" (*) [EOF],
+            T = "(" E ")" (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "(" E (*) ")" [")"],
+            T = "(" E (*) ")" ["-"],
+            E = E (*) "-" T [")"],
+            E = E (*) "-" T ["-"]
+        ],
+        shifts: [
+            (")", S15),
+            ("-", S11)
+        ],
+        gotos: []
+    },
+    State {
+        items: [
+            E = E "-" T (*) [")"],
+            E = E "-" T (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    },
+    State {
+        items: [
+            T = "(" E ")" (*) [")"],
+            T = "(" E ")" (*) ["-"]
+        ],
+        shifts: [],
+        gotos: []
+    }
+]"#);
+
+}

src/util.rs

@@ -1,4 +1,7 @@
+use std::collections::{hash_map, HashMap, HashSet};
 use std::fmt::{Display, Formatter, Error};
+use std::hash::Hash;
+use std::iter::FromIterator;
 
 pub struct Sep<S>(pub &'static str, pub S);
 
@@ -29,3 +32,49 @@ impl<'a,S:Display> Display for Prefix<&'a [S]> {
     }
 }
 
+pub struct Multimap<K,V> {
+    map: HashMap<K,Vec<V>>
+}
+
+impl<K:Hash+Eq,V> Multimap<K,V> {
+    pub fn new() -> Multimap<K,V> {
+        Multimap { map: map() }
+    }
+
+    pub fn push(&mut self, key: K, value: V) {
+        self.map.entry(key).or_insert(vec![]).push(value);
+    }
+
+    pub fn get(&self, key: &K) -> &[V] {
+        match self.map.get(key) {
+            Some(v) => v,
+            None => &[]
+        }
+    }
+
+    pub fn into_iter(self) -> hash_map::IntoIter<K, Vec<V>> {
+        self.map.into_iter()
+    }
+}
+
+impl<K:Hash+Eq,V> FromIterator<(K,V)> for Multimap<K,V> {
+    fn from_iter<T>(iterator: T) -> Self where T: IntoIterator<Item=(K,V)> {
+        let mut map = Multimap::new();
+        for (key, value) in iterator {
+            map.push(key, value);
+        }
+        map
+    }
+}
+
+pub type Map<K,V> = HashMap<K,V>;
+
+pub fn map<K:Hash+Eq,V>() -> HashMap<K,V> {
+    HashMap::new()
+}
+
+pub type Set<K> = HashSet<K>;
+
+pub fn set<K:Hash+Eq>() -> HashSet<K> {
+    HashSet::new()
+}