506 lines
19 KiB
Rust
506 lines
19 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Machinery for hygienic macros, as described in the MTWT[1] paper.
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//!
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//! [1] Matthew Flatt, Ryan Culpepper, David Darais, and Robert Bruce Findler.
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//! 2012. *Macros that work together: Compile-time bindings, partial expansion,
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//! and definition contexts*. J. Funct. Program. 22, 2 (March 2012), 181-216.
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//! DOI=10.1017/S0956796812000093 http://dx.doi.org/10.1017/S0956796812000093
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use ast::{Ident, Mrk, Name, SyntaxContext};
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use std::cell::RefCell;
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use std::rc::Rc;
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use std::collections::HashMap;
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// the SCTable contains a table of SyntaxContext_'s. It
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// represents a flattened tree structure, to avoid having
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// managed pointers everywhere (that caused an ICE).
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// the mark_memo and rename_memo fields are side-tables
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// that ensure that adding the same mark to the same context
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// gives you back the same context as before. This shouldn't
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// change the semantics--everything here is immutable--but
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// it should cut down on memory use *a lot*; applying a mark
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// to a tree containing 50 identifiers would otherwise generate
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// 50 new contexts
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pub struct SCTable {
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table: RefCell<Vec<SyntaxContext_>>,
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mark_memo: RefCell<HashMap<(SyntaxContext,Mrk),SyntaxContext>>,
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rename_memo: RefCell<HashMap<(SyntaxContext,Ident,Name),SyntaxContext>>,
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}
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#[deriving(PartialEq, Encodable, Decodable, Hash)]
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pub enum SyntaxContext_ {
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EmptyCtxt,
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Mark (Mrk,SyntaxContext),
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// flattening the name and syntaxcontext into the rename...
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// HIDDEN INVARIANTS:
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// 1) the first name in a Rename node
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// can only be a programmer-supplied name.
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// 2) Every Rename node with a given Name in the
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// "to" slot must have the same name and context
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// in the "from" slot. In essence, they're all
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// pointers to a single "rename" event node.
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Rename (Ident,Name,SyntaxContext),
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// actually, IllegalCtxt may not be necessary.
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IllegalCtxt
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}
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/// A list of ident->name renamings
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pub type RenameList = Vec<(Ident, Name)>;
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/// Extend a syntax context with a given mark
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pub fn apply_mark(m: Mrk, ctxt: SyntaxContext) -> SyntaxContext {
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with_sctable(|table| apply_mark_internal(m, ctxt, table))
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}
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// Extend a syntax context with a given mark and sctable (explicit memoization)
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fn apply_mark_internal(m: Mrk, ctxt: SyntaxContext, table: &SCTable) -> SyntaxContext {
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let key = (ctxt, m);
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let new_ctxt = |_: &(SyntaxContext, Mrk)|
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idx_push(&mut *table.table.borrow_mut(), Mark(m, ctxt));
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*table.mark_memo.borrow_mut().find_or_insert_with(key, new_ctxt)
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}
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/// Extend a syntax context with a given rename
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pub fn apply_rename(id: Ident, to:Name,
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ctxt: SyntaxContext) -> SyntaxContext {
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with_sctable(|table| apply_rename_internal(id, to, ctxt, table))
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}
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// Extend a syntax context with a given rename and sctable (explicit memoization)
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fn apply_rename_internal(id: Ident,
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to: Name,
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ctxt: SyntaxContext,
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table: &SCTable) -> SyntaxContext {
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let key = (ctxt,id,to);
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let new_ctxt = |_: &(SyntaxContext, Ident, Mrk)|
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idx_push(&mut *table.table.borrow_mut(), Rename(id, to, ctxt));
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*table.rename_memo.borrow_mut().find_or_insert_with(key, new_ctxt)
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}
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/// Apply a list of renamings to a context
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// if these rename lists get long, it would make sense
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// to consider memoizing this fold. This may come up
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// when we add hygiene to item names.
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pub fn apply_renames(renames: &RenameList, ctxt: SyntaxContext) -> SyntaxContext {
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renames.iter().fold(ctxt, |ctxt, &(from, to)| {
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apply_rename(from, to, ctxt)
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})
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}
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/// Fetch the SCTable from TLS, create one if it doesn't yet exist.
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pub fn with_sctable<T>(op: |&SCTable| -> T) -> T {
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local_data_key!(sctable_key: Rc<SCTable>)
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match sctable_key.get() {
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Some(ts) => op(&**ts),
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None => {
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let ts = Rc::new(new_sctable_internal());
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sctable_key.replace(Some(ts.clone()));
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op(&*ts)
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}
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}
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}
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// Make a fresh syntax context table with EmptyCtxt in slot zero
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// and IllegalCtxt in slot one.
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fn new_sctable_internal() -> SCTable {
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SCTable {
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table: RefCell::new(vec!(EmptyCtxt, IllegalCtxt)),
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mark_memo: RefCell::new(HashMap::new()),
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rename_memo: RefCell::new(HashMap::new()),
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}
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}
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/// Print out an SCTable for debugging
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pub fn display_sctable(table: &SCTable) {
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error!("SC table:");
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for (idx,val) in table.table.borrow().iter().enumerate() {
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error!("{:4u} : {:?}",idx,val);
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}
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}
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/// Clear the tables from TLD to reclaim memory.
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pub fn clear_tables() {
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with_sctable(|table| {
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*table.table.borrow_mut() = Vec::new();
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*table.mark_memo.borrow_mut() = HashMap::new();
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*table.rename_memo.borrow_mut() = HashMap::new();
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});
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with_resolve_table_mut(|table| *table = HashMap::new());
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}
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// Add a value to the end of a vec, return its index
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fn idx_push<T>(vec: &mut Vec<T> , val: T) -> u32 {
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vec.push(val);
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(vec.len() - 1) as u32
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}
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/// Resolve a syntax object to a name, per MTWT.
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pub fn resolve(id: Ident) -> Name {
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with_sctable(|sctable| {
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with_resolve_table_mut(|resolve_table| {
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resolve_internal(id, sctable, resolve_table)
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})
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})
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}
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type ResolveTable = HashMap<(Name,SyntaxContext),Name>;
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// okay, I admit, putting this in TLS is not so nice:
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// fetch the SCTable from TLS, create one if it doesn't yet exist.
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fn with_resolve_table_mut<T>(op: |&mut ResolveTable| -> T) -> T {
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local_data_key!(resolve_table_key: Rc<RefCell<ResolveTable>>)
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match resolve_table_key.get() {
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Some(ts) => op(&mut *ts.borrow_mut()),
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None => {
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let ts = Rc::new(RefCell::new(HashMap::new()));
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resolve_table_key.replace(Some(ts.clone()));
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op(&mut *ts.borrow_mut())
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}
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}
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}
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// Resolve a syntax object to a name, per MTWT.
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// adding memoization to resolve 500+ seconds in resolve for librustc (!)
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fn resolve_internal(id: Ident,
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table: &SCTable,
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resolve_table: &mut ResolveTable) -> Name {
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let key = (id.name, id.ctxt);
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match resolve_table.find(&key) {
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Some(&name) => return name,
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None => {}
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}
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let resolved = {
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let result = *table.table.borrow().get(id.ctxt as uint);
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match result {
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EmptyCtxt => id.name,
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// ignore marks here:
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Mark(_,subctxt) =>
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resolve_internal(Ident{name:id.name, ctxt: subctxt},
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table, resolve_table),
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// do the rename if necessary:
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Rename(Ident{name, ctxt}, toname, subctxt) => {
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let resolvedfrom =
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resolve_internal(Ident{name:name, ctxt:ctxt},
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table, resolve_table);
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let resolvedthis =
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resolve_internal(Ident{name:id.name, ctxt:subctxt},
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table, resolve_table);
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if (resolvedthis == resolvedfrom)
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&& (marksof_internal(ctxt, resolvedthis, table)
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== marksof_internal(subctxt, resolvedthis, table)) {
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toname
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} else {
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resolvedthis
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}
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}
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IllegalCtxt => fail!("expected resolvable context, got IllegalCtxt")
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}
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};
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resolve_table.insert(key, resolved);
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resolved
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}
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/// Compute the marks associated with a syntax context.
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pub fn marksof(ctxt: SyntaxContext, stopname: Name) -> Vec<Mrk> {
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with_sctable(|table| marksof_internal(ctxt, stopname, table))
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}
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// the internal function for computing marks
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// it's not clear to me whether it's better to use a [] mutable
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// vector or a cons-list for this.
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fn marksof_internal(ctxt: SyntaxContext,
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stopname: Name,
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table: &SCTable) -> Vec<Mrk> {
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let mut result = Vec::new();
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let mut loopvar = ctxt;
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loop {
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let table_entry = *table.table.borrow().get(loopvar as uint);
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match table_entry {
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EmptyCtxt => {
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return result;
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},
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Mark(mark, tl) => {
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xor_push(&mut result, mark);
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loopvar = tl;
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},
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Rename(_,name,tl) => {
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// see MTWT for details on the purpose of the stopname.
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// short version: it prevents duplication of effort.
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if name == stopname {
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return result;
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} else {
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loopvar = tl;
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}
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}
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IllegalCtxt => fail!("expected resolvable context, got IllegalCtxt")
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}
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}
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}
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/// Return the outer mark for a context with a mark at the outside.
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/// FAILS when outside is not a mark.
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pub fn outer_mark(ctxt: SyntaxContext) -> Mrk {
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with_sctable(|sctable| {
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match *sctable.table.borrow().get(ctxt as uint) {
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Mark(mrk, _) => mrk,
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_ => fail!("can't retrieve outer mark when outside is not a mark")
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}
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})
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}
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// Push a name... unless it matches the one on top, in which
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// case pop and discard (so two of the same marks cancel)
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fn xor_push(marks: &mut Vec<Mrk>, mark: Mrk) {
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if (marks.len() > 0) && (*marks.last().unwrap() == mark) {
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marks.pop().unwrap();
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} else {
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marks.push(mark);
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}
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}
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#[cfg(test)]
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mod tests {
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use ast::{EMPTY_CTXT, Ident, Mrk, Name, SyntaxContext};
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use super::{resolve, xor_push, apply_mark_internal, new_sctable_internal};
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use super::{apply_rename_internal, apply_renames, marksof_internal, resolve_internal};
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use super::{SCTable, EmptyCtxt, Mark, Rename, IllegalCtxt};
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use std::collections::HashMap;
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#[test]
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fn xorpush_test () {
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let mut s = Vec::new();
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xor_push(&mut s, 14);
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assert_eq!(s.clone(), vec!(14));
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xor_push(&mut s, 14);
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assert_eq!(s.clone(), Vec::new());
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xor_push(&mut s, 14);
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assert_eq!(s.clone(), vec!(14));
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xor_push(&mut s, 15);
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assert_eq!(s.clone(), vec!(14, 15));
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xor_push(&mut s, 16);
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assert_eq!(s.clone(), vec!(14, 15, 16));
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xor_push(&mut s, 16);
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assert_eq!(s.clone(), vec!(14, 15));
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xor_push(&mut s, 15);
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assert_eq!(s.clone(), vec!(14));
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}
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fn id(n: Name, s: SyntaxContext) -> Ident {
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Ident {name: n, ctxt: s}
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}
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// because of the SCTable, I now need a tidy way of
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// creating syntax objects. Sigh.
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#[deriving(Clone, PartialEq, Show)]
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enum TestSC {
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M(Mrk),
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R(Ident,Name)
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}
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// unfold a vector of TestSC values into a SCTable,
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// returning the resulting index
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fn unfold_test_sc(tscs : Vec<TestSC> , tail: SyntaxContext, table: &SCTable)
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-> SyntaxContext {
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tscs.iter().rev().fold(tail, |tail : SyntaxContext, tsc : &TestSC|
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{match *tsc {
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M(mrk) => apply_mark_internal(mrk,tail,table),
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R(ident,name) => apply_rename_internal(ident,name,tail,table)}})
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}
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// gather a SyntaxContext back into a vector of TestSCs
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fn refold_test_sc(mut sc: SyntaxContext, table : &SCTable) -> Vec<TestSC> {
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let mut result = Vec::new();
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loop {
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let table = table.table.borrow();
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match *table.get(sc as uint) {
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EmptyCtxt => {return result;},
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Mark(mrk,tail) => {
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result.push(M(mrk));
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sc = tail;
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continue;
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},
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Rename(id,name,tail) => {
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result.push(R(id,name));
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sc = tail;
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continue;
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}
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IllegalCtxt => fail!("expected resolvable context, got IllegalCtxt")
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}
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}
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}
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#[test]
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fn test_unfold_refold(){
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let mut t = new_sctable_internal();
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let test_sc = vec!(M(3),R(id(101,0),14),M(9));
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assert_eq!(unfold_test_sc(test_sc.clone(),EMPTY_CTXT,&mut t),4);
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{
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let table = t.table.borrow();
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assert!(*table.get(2) == Mark(9,0));
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assert!(*table.get(3) == Rename(id(101,0),14,2));
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assert!(*table.get(4) == Mark(3,3));
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}
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assert_eq!(refold_test_sc(4,&t),test_sc);
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}
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// extend a syntax context with a sequence of marks given
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// in a vector. v[0] will be the outermost mark.
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fn unfold_marks(mrks: Vec<Mrk> , tail: SyntaxContext, table: &SCTable)
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-> SyntaxContext {
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mrks.iter().rev().fold(tail, |tail:SyntaxContext, mrk:&Mrk|
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{apply_mark_internal(*mrk,tail,table)})
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}
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#[test] fn unfold_marks_test() {
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let mut t = new_sctable_internal();
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assert_eq!(unfold_marks(vec!(3,7),EMPTY_CTXT,&mut t),3);
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{
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let table = t.table.borrow();
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assert!(*table.get(2) == Mark(7,0));
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assert!(*table.get(3) == Mark(3,2));
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}
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}
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#[test]
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fn test_marksof () {
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let stopname = 242;
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let name1 = 243;
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let mut t = new_sctable_internal();
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assert_eq!(marksof_internal (EMPTY_CTXT,stopname,&t),Vec::new());
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// FIXME #5074: ANF'd to dodge nested calls
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{ let ans = unfold_marks(vec!(4,98),EMPTY_CTXT,&mut t);
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assert_eq! (marksof_internal (ans,stopname,&t),vec!(4,98));}
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// does xoring work?
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{ let ans = unfold_marks(vec!(5,5,16),EMPTY_CTXT,&mut t);
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assert_eq! (marksof_internal (ans,stopname,&t), vec!(16));}
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// does nested xoring work?
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{ let ans = unfold_marks(vec!(5,10,10,5,16),EMPTY_CTXT,&mut t);
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assert_eq! (marksof_internal (ans, stopname,&t), vec!(16));}
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// rename where stop doesn't match:
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{ let chain = vec!(M(9),
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R(id(name1,
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apply_mark_internal (4, EMPTY_CTXT,&mut t)),
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100101102),
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M(14));
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let ans = unfold_test_sc(chain,EMPTY_CTXT,&mut t);
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assert_eq! (marksof_internal (ans, stopname, &t), vec!(9,14));}
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// rename where stop does match
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{ let name1sc = apply_mark_internal(4, EMPTY_CTXT, &mut t);
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let chain = vec!(M(9),
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R(id(name1, name1sc),
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stopname),
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M(14));
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let ans = unfold_test_sc(chain,EMPTY_CTXT,&mut t);
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assert_eq! (marksof_internal (ans, stopname, &t), vec!(9)); }
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}
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#[test]
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fn resolve_tests () {
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let a = 40;
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let mut t = new_sctable_internal();
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let mut rt = HashMap::new();
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// - ctxt is MT
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assert_eq!(resolve_internal(id(a,EMPTY_CTXT),&mut t, &mut rt),a);
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// - simple ignored marks
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{ let sc = unfold_marks(vec!(1,2,3),EMPTY_CTXT,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),a);}
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// - orthogonal rename where names don't match
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{ let sc = unfold_test_sc(vec!(R(id(50,EMPTY_CTXT),51),M(12)),EMPTY_CTXT,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),a);}
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// - rename where names do match, but marks don't
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{ let sc1 = apply_mark_internal(1,EMPTY_CTXT,&mut t);
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let sc = unfold_test_sc(vec!(R(id(a,sc1),50),
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M(1),
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M(2)),
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EMPTY_CTXT,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), a);}
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// - rename where names and marks match
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{ let sc1 = unfold_test_sc(vec!(M(1),M(2)),EMPTY_CTXT,&mut t);
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let sc = unfold_test_sc(vec!(R(id(a,sc1),50),M(1),M(2)),EMPTY_CTXT,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 50); }
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// - rename where names and marks match by literal sharing
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{ let sc1 = unfold_test_sc(vec!(M(1),M(2)),EMPTY_CTXT,&mut t);
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let sc = unfold_test_sc(vec!(R(id(a,sc1),50)),sc1,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 50); }
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// - two renames of the same var.. can only happen if you use
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// local-expand to prevent the inner binding from being renamed
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// during the rename-pass caused by the first:
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println!("about to run bad test");
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{ let sc = unfold_test_sc(vec!(R(id(a,EMPTY_CTXT),50),
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R(id(a,EMPTY_CTXT),51)),
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EMPTY_CTXT,&mut t);
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assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt), 51); }
|
|
// the simplest double-rename:
|
|
{ let a_to_a50 = apply_rename_internal(id(a,EMPTY_CTXT),50,EMPTY_CTXT,&mut t);
|
|
let a50_to_a51 = apply_rename_internal(id(a,a_to_a50),51,a_to_a50,&mut t);
|
|
assert_eq!(resolve_internal(id(a,a50_to_a51),&mut t, &mut rt),51);
|
|
// mark on the outside doesn't stop rename:
|
|
let sc = apply_mark_internal(9,a50_to_a51,&mut t);
|
|
assert_eq!(resolve_internal(id(a,sc),&mut t, &mut rt),51);
|
|
// but mark on the inside does:
|
|
let a50_to_a51_b = unfold_test_sc(vec!(R(id(a,a_to_a50),51),
|
|
M(9)),
|
|
a_to_a50,
|
|
&mut t);
|
|
assert_eq!(resolve_internal(id(a,a50_to_a51_b),&mut t, &mut rt),50);}
|
|
}
|
|
|
|
#[test]
|
|
fn mtwt_resolve_test(){
|
|
let a = 40;
|
|
assert_eq!(resolve(id(a,EMPTY_CTXT)),a);
|
|
}
|
|
|
|
|
|
#[test]
|
|
fn hashing_tests () {
|
|
let mut t = new_sctable_internal();
|
|
assert_eq!(apply_mark_internal(12,EMPTY_CTXT,&mut t),2);
|
|
assert_eq!(apply_mark_internal(13,EMPTY_CTXT,&mut t),3);
|
|
// using the same one again should result in the same index:
|
|
assert_eq!(apply_mark_internal(12,EMPTY_CTXT,&mut t),2);
|
|
// I'm assuming that the rename table will behave the same....
|
|
}
|
|
|
|
#[test]
|
|
fn resolve_table_hashing_tests() {
|
|
let mut t = new_sctable_internal();
|
|
let mut rt = HashMap::new();
|
|
assert_eq!(rt.len(),0);
|
|
resolve_internal(id(30,EMPTY_CTXT),&mut t, &mut rt);
|
|
assert_eq!(rt.len(),1);
|
|
resolve_internal(id(39,EMPTY_CTXT),&mut t, &mut rt);
|
|
assert_eq!(rt.len(),2);
|
|
resolve_internal(id(30,EMPTY_CTXT),&mut t, &mut rt);
|
|
assert_eq!(rt.len(),2);
|
|
}
|
|
|
|
#[test]
|
|
fn new_resolves_test() {
|
|
let renames = vec!((Ident{name:23,ctxt:EMPTY_CTXT},24),
|
|
(Ident{name:29,ctxt:EMPTY_CTXT},29));
|
|
let new_ctxt1 = apply_renames(&renames,EMPTY_CTXT);
|
|
assert_eq!(resolve(Ident{name:23,ctxt:new_ctxt1}),24);
|
|
assert_eq!(resolve(Ident{name:29,ctxt:new_ctxt1}),29);
|
|
}
|
|
}
|