93 lines
2.9 KiB
Rust
93 lines
2.9 KiB
Rust
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use super::{
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FnEvalContext,
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CachedMir,
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TerminatorTarget,
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};
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use error::EvalResult;
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use rustc::mir::repr as mir;
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pub enum Event<'a, 'tcx: 'a> {
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Assignment(&'a mir::Statement<'tcx>),
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Terminator(&'a mir::Terminator<'tcx>),
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Done,
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}
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pub struct Stepper<'fncx, 'a: 'fncx, 'b: 'a + 'mir, 'mir: 'fncx, 'tcx: 'b>{
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fncx: &'fncx mut FnEvalContext<'a, 'b, 'mir, 'tcx>,
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block: mir::BasicBlock,
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stmt: usize,
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mir: CachedMir<'mir, 'tcx>,
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process: fn (&mut Stepper<'fncx, 'a, 'b, 'mir, 'tcx>) -> EvalResult<()>,
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}
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impl<'fncx, 'a, 'b: 'a + 'mir, 'mir, 'tcx: 'b> Stepper<'fncx, 'a, 'b, 'mir, 'tcx> {
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pub(super) fn new(fncx: &'fncx mut FnEvalContext<'a, 'b, 'mir, 'tcx>) -> Self {
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Stepper {
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block: fncx.frame().next_block,
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mir: fncx.mir(),
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fncx: fncx,
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stmt: 0,
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process: Self::dummy,
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}
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}
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fn dummy(&mut self) -> EvalResult<()> { Ok(()) }
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fn statement(&mut self) -> EvalResult<()> {
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let block_data = self.mir.basic_block_data(self.block);
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let stmt = &block_data.statements[self.stmt];
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let mir::StatementKind::Assign(ref lvalue, ref rvalue) = stmt.kind;
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let result = self.fncx.eval_assignment(lvalue, rvalue);
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self.fncx.maybe_report(stmt.span, result)?;
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self.stmt += 1;
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Ok(())
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}
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fn terminator(&mut self) -> EvalResult<()> {
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self.stmt = 0;
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let term = {
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let block_data = self.mir.basic_block_data(self.block);
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let terminator = block_data.terminator();
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let result = self.fncx.eval_terminator(terminator);
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self.fncx.maybe_report(terminator.span, result)?
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};
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match term {
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TerminatorTarget::Block(block) => {
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self.block = block;
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},
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TerminatorTarget::Return => {
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self.fncx.pop_stack_frame();
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self.fncx.name_stack.pop();
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if !self.fncx.stack.is_empty() {
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self.block = self.fncx.frame().next_block;
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self.mir = self.fncx.mir();
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}
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},
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TerminatorTarget::Call => {
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self.block = self.fncx.frame().next_block;
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self.mir = self.fncx.mir();
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},
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}
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Ok(())
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}
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pub fn step<'step>(&'step mut self) -> EvalResult<Event<'step, 'tcx>> {
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(self.process)(self)?;
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if self.fncx.stack.is_empty() {
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// fuse the iterator
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self.process = Self::dummy;
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return Ok(Event::Done);
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}
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let basic_block = self.mir.basic_block_data(self.block);
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if let Some(stmt) = basic_block.statements.get(self.stmt) {
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self.process = Self::statement;
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return Ok(Event::Assignment(&stmt));
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}
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self.process = Self::terminator;
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Ok(Event::Terminator(basic_block.terminator()))
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}
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pub fn block(&self) -> mir::BasicBlock {
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self.block
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}
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}
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