267 lines
9.0 KiB
Rust
267 lines
9.0 KiB
Rust
use prolog_parser::ast::*;
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use prolog::instructions::*;
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use std::collections::{HashMap, VecDeque};
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use std::hash::Hash;
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#[derive(Clone, Copy)]
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enum IntIndex {
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External(usize), Fail, Internal(usize)
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}
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pub struct CodeOffsets {
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flags: MachineFlags,
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pub constants: HashMap<Constant, ThirdLevelIndex>,
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pub lists: ThirdLevelIndex,
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pub structures: HashMap<(ClauseName, usize), ThirdLevelIndex>
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}
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impl CodeOffsets {
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pub fn new(flags: MachineFlags) -> Self {
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CodeOffsets {
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flags,
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constants: HashMap::new(),
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lists: Vec::new(),
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structures: HashMap::new()
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}
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}
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fn cap_choice_seq_with_trust(prelude: &mut ThirdLevelIndex) {
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prelude.last_mut().map(|instr| {
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match instr {
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&mut IndexedChoiceInstruction::Retry(i) =>
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*instr = IndexedChoiceInstruction::Trust(i),
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_ => {}
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};
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});
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}
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fn add_index(is_first_index: bool, index: usize) -> IndexedChoiceInstruction {
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if is_first_index {
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IndexedChoiceInstruction::Try(index)
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} else {
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IndexedChoiceInstruction::Retry(index)
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}
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}
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pub fn index_term(&mut self, first_arg: &Term, index: usize)
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{
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match first_arg {
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&Term::Clause(_, ref name, ref terms, _) => {
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let code = self.structures.entry((name.clone(), terms.len()))
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.or_insert(Vec::new());
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let is_initial_index = code.is_empty();
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code.push(Self::add_index(is_initial_index, index));
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},
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&Term::Cons(..) => {
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let is_initial_index = self.lists.is_empty();
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self.lists.push(Self::add_index(is_initial_index, index));
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},
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&Term::Constant(_, Constant::String(ref s))
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if !self.flags.double_quotes.is_atom() && !s.is_empty() => { // strings are lists in this case.
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let is_initial_index = self.lists.is_empty();
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self.lists.push(Self::add_index(is_initial_index, index));
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},
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&Term::Constant(_, Constant::String(ref s))
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if !self.flags.double_quotes.is_atom() && s.is_expandable() => {
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let is_initial_index = self.lists.is_empty();
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self.lists.push(Self::add_index(is_initial_index, index));
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},
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&Term::Constant(_, ref constant) => {
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let code = self.constants.entry(constant.clone())
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.or_insert(Vec::new());
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let is_initial_index = code.is_empty();
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code.push(Self::add_index(is_initial_index, index));
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},
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_ => {}
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};
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}
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fn second_level_index<Index>(indices: HashMap<Index, ThirdLevelIndex>, prelude: &mut CodeDeque)
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-> HashMap<Index, IntIndex>
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where Index: Eq + Hash
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{
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let mut index_locs = HashMap::new();
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for (key, mut code) in indices.into_iter() {
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if code.len() > 1 {
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index_locs.insert(key, IntIndex::Internal(prelude.len()));
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Self::cap_choice_seq_with_trust(&mut code);
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prelude.extend(code.into_iter().map(|code| Line::from(code)));
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} else {
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code.first().map(|i| {
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index_locs.insert(key, IntIndex::External(i.offset()));
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});
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}
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}
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index_locs
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}
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fn no_indices(&self) -> bool {
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let no_constants = self.constants.is_empty();
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let no_structures = self.structures.is_empty();
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let no_lists = self.lists.is_empty();
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no_constants && no_structures && no_lists
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}
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fn flatten_index<Index>(index: HashMap<Index, IntIndex>, len: usize)
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-> HashMap<Index, usize>
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where Index: Eq + Hash
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{
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let mut flattened_index = HashMap::new();
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for (key, int_index) in index.into_iter() {
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match int_index {
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IntIndex::External(offset) => {
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flattened_index.insert(key, offset + len + 1);
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},
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IntIndex::Internal(offset) => {
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flattened_index.insert(key, offset + 1);
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},
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_ => {}
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};
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}
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flattened_index
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}
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fn adjust_internal_index(index: IntIndex) -> IntIndex
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{
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match index {
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IntIndex::Internal(o) => IntIndex::Internal(o + 1),
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IntIndex::External(o) => IntIndex::External(o),
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_ => IntIndex::Fail
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}
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}
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fn switch_on_constant(con_ind: HashMap<Constant, ThirdLevelIndex>, prelude: &mut CodeDeque)
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-> IntIndex
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{
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let con_ind = Self::second_level_index(con_ind, prelude);
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if con_ind.len() > 1 {
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let index = Self::flatten_index(con_ind, prelude.len());
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let instr = IndexingInstruction::SwitchOnConstant(index.len(), index);
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prelude.push_front(Line::from(instr));
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IntIndex::Internal(1)
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} else {
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con_ind.values().next()
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.map(|index| Self::adjust_internal_index(*index))
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.unwrap_or(IntIndex::Fail)
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}
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}
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fn switch_on_structure(str_ind: HashMap<(ClauseName, usize), ThirdLevelIndex>,
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prelude: &mut CodeDeque)
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-> IntIndex
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{
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let str_ind = Self::second_level_index(str_ind, prelude);
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if str_ind.len() > 1 {
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let index = Self::flatten_index(str_ind, prelude.len());
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let instr = IndexingInstruction::SwitchOnStructure(index.len(), index);
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prelude.push_front(Line::from(instr));
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IntIndex::Internal(1)
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} else {
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str_ind.values().next()
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.map(|index| Self::adjust_internal_index(*index))
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.unwrap_or(IntIndex::Fail)
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}
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}
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fn switch_on_list(mut lists: ThirdLevelIndex, prelude: &mut CodeDeque) -> IntIndex
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{
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if lists.len() > 1 {
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Self::cap_choice_seq_with_trust(&mut lists);
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prelude.extend(lists.into_iter().map(|i| Line::from(i)));
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IntIndex::Internal(0)
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} else {
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lists.first()
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.map(|i| IntIndex::External(i.offset()))
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.unwrap_or(IntIndex::Fail)
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}
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}
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fn switch_on_str_offset_from(str_loc: IntIndex, prelude_len: usize, con_loc: IntIndex)
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-> usize
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{
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match str_loc {
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IntIndex::External(o) => o + prelude_len + 1,
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IntIndex::Fail => 0,
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IntIndex::Internal(_) => match con_loc {
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IntIndex::Internal(_) => 2,
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_ => 1
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}
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}
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}
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fn switch_on_con_offset_from(con_loc: IntIndex, prelude_len: usize) -> usize
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{
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match con_loc {
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IntIndex::External(offset) => offset + prelude_len + 1,
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IntIndex::Fail => 0,
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IntIndex::Internal(offset) => offset,
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}
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}
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fn switch_on_lst_offset_from(lst_loc: IntIndex, prelude_len: usize, lst_offset: usize)
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-> usize
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{
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match lst_loc {
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IntIndex::External(o) => o + prelude_len + 1,
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IntIndex::Fail => 0,
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IntIndex::Internal(_) => prelude_len - lst_offset + 1
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}
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}
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pub fn add_indices(self, code: &mut Code, mut code_body: Code)
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{
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if self.no_indices() {
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*code = code_body;
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return;
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}
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let mut prelude = VecDeque::new();
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let lst_loc = Self::switch_on_list(self.lists, &mut prelude);
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let lst_offset = prelude.len();
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let str_loc = Self::switch_on_structure(self.structures, &mut prelude);
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let con_loc = Self::switch_on_constant(self.constants, &mut prelude);
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let prelude_length = prelude.len();
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for (index, line) in prelude.iter_mut().enumerate() {
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match line {
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&mut Line::IndexedChoice(IndexedChoiceInstruction::Try(ref mut i))
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| &mut Line::IndexedChoice(IndexedChoiceInstruction::Retry(ref mut i))
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| &mut Line::IndexedChoice(IndexedChoiceInstruction::Trust(ref mut i)) =>
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*i += prelude_length - index,
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_ => {}
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}
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}
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let str_loc = Self::switch_on_str_offset_from(str_loc, prelude.len(), con_loc);
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let con_loc = Self::switch_on_con_offset_from(con_loc, prelude.len());
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let lst_loc = Self::switch_on_lst_offset_from(lst_loc, prelude.len(), lst_offset);
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let switch_instr = IndexingInstruction::SwitchOnTerm(prelude.len() + 1,
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con_loc,
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lst_loc,
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str_loc);
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prelude.push_front(Line::from(switch_instr));
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*code = Vec::from(prelude);
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code.append(&mut code_body);
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}
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}
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