TypeTerm: first implementation of curry/decurry, normalize etc.
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1 changed files with 181 additions and 17 deletions
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@ -10,6 +10,7 @@ use {
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#[derive(Clone, PartialEq, Eq, Hash, Debug)]
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pub enum TypeTerm {
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/* Atomic Terms */
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// Base types from dictionary
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@ -19,6 +20,7 @@ pub enum TypeTerm {
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Num(i64),
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Char(char),
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/* Complex Terms */
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@ -62,29 +64,183 @@ impl TypeTerm {
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self.arg(TypeTerm::Char(c))
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}
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/* TODO
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// summarize all curried applications into one vec
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pub fn decurry() {}
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// transmute into Ladder-Normal-Form
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pub fn normalize(&mut self) {
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/// transform term to have at max 2 entries in Application list
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pub fn curry(&self) -> Self {
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match self {
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TypeTerm::Apply{ id, args } => {
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TypeTerm::App(head) => {
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let mut head = head.clone();
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if head.len() > 2 {
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let mut tail = head.split_off(2);
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TypeTerm::App(vec![
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TypeTerm::App(head),
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if tail.len() > 1 {
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TypeTerm::App(tail).curry()
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} else {
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tail.remove(0)
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}
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])
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} else {
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TypeTerm::App(head)
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}
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}
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TypeTerm::Ladder(l) => {
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TypeTerm::Ladder( l.iter().map(|x| x.curry()).collect() )
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}
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atom => { atom.clone() }
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}
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}
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/// summarize all curried applications into one vec
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pub fn decurry(&mut self) -> &mut Self {
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match self {
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TypeTerm::App(args) => {
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if args.len() > 0 {
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let mut a0 = args.remove(0);
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a0.decurry();
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match a0 {
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TypeTerm::App(sub_args) => {
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for (i,x) in sub_args.into_iter().enumerate() {
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args.insert(i, x);
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}
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}
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other => { args.insert(0, other); }
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}
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}
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}
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TypeTerm::Ladder(args) => {
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for x in args.iter_mut() {
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x.decurry();
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}
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}
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_ => {}
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}
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self
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}
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/// does the type contain ladders (false) or is it 'flat' (true) ?
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pub fn is_flat(&self) -> bool {
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match self {
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TypeTerm::TypeID(_) => true,
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TypeTerm::Num(_) => true,
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TypeTerm::Char(_) => true,
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TypeTerm::App(args) => args.iter().fold(true, |s,x| s && x.is_flat()),
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TypeTerm::Ladder(_) => false
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}
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}
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/// transmute self into Ladder-Normal-Form
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///
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/// Example:
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/// <Seq <Digit 10>~Char> ⇒ <Seq <Digit 10>>~<Seq Char>
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pub fn normalize(self) -> Self {
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let mut new_ladder = Vec::<TypeTerm>::new();
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match self {
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TypeTerm::Ladder(args) => {
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for x in args.into_iter() {
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new_ladder.push(x.normalize());
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}
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}
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TypeTerm::App(args) => {
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let mut args_iter = args.into_iter();
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if let Some(head) = args_iter.next() {
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let mut stage1_args = vec![ head.clone() ];
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let mut stage2_args = vec![ head.clone() ];
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let mut done = false;
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for x in args_iter {
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match x.normalize() {
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TypeTerm::Ladder(mut ladder) => {
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// normalize this ladder
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if !done {
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if ladder.len() > 2 {
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stage1_args.push( ladder.remove(0) );
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stage2_args.push( TypeTerm::Ladder(ladder.to_vec()) );
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done = true;
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} else if ladder.len() == 1 {
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stage1_args.push( ladder[0].clone() );
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stage2_args.push( ladder[0].clone() );
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} else {
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// empty type ?
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}
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} else {
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stage1_args.push( TypeTerm::Ladder(ladder.clone()) );
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stage2_args.push( TypeTerm::Ladder(ladder.clone()) );
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}
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},
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_ => {
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unreachable!("x is in LNF");
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}
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}
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}
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new_ladder.push(TypeTerm::Ladder(stage1_args));
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new_ladder.push(TypeTerm::Ladder(stage2_args));
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}
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}
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atom => {
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new_ladder.push(atom);
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}
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}
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TypeTerm::Ladder( new_ladder )
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}
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/*
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pub fn is_supertype_of(&self, t: &TypeTerm) -> bool {
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t.is_semantic_subtype_of(self)
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}
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*/
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// returns provided syntax-type,
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pub fn is_semantic_subtype_of(&self, expected_type: &TypeTerm) -> Option< TypeTerm > {
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let mut provided_lnf = self.clone();
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let mut expected_lnf = expected_type.clone();
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match
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(provided_lnf.normalize(),
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expected_lnf.normalize())
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{
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( TypeTerm::Ladder( provided_ladder ),
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TypeTerm::Ladder( expected_ladder )
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) => {
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for i in 0..provided_ladder.len() {
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if provided_ladder[i] == expected_ladder[0] {
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return Some(TypeTerm::Ladder(
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provided_ladder[i..].into_iter().cloned().collect()
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))
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}
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}
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None
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},
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_ => {
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// both are in LNF!
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unreachable!()
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}
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}
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}
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pub fn is_supertype_of(&self, t: &TypeTerm) -> bool {
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t.is_subtype_of(self)
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pub fn is_syntactic_subtype_of(&self, expected_type: &TypeTerm) -> bool {
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if let Some(provided_type) = self.is_semantic_subtype_of( expected_type ) {
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&provided_type == expected_type
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} else {
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false
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}
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}
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pub fn is_subtype_of(&self, t: &TypeTerm) -> bool {
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false
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}
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*/
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pub fn from_str(s: &str, names: &HashMap<String, TypeID>) -> Option<Self> {
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let mut term_stack = Vec::<Option<TypeTerm>>::new();
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@ -152,8 +308,14 @@ impl TypeTerm {
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out.push_str(&"<");
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let mut first = true;
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for x in args.iter() {
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out.push_str(&" ");
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if !first {
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out.push_str(&" ");
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} else {
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first = false;
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}
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out.push_str(&x.to_str(names));
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}
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@ -169,8 +331,10 @@ impl TypeTerm {
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for x in l.iter() {
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if !first {
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out.push_str(&"~");
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} else {
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first = false;
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}
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out.push_str(&x.to_str(names));
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}
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