爱特每羊队
27 lines
1.0 KiB
Rust
27 lines
1.0 KiB
Rust
//! while 语句 emit：`emit_while_statement` 先测条件后执行体。
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use crate::{CompileCtx, Emitter};
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use oxide_ir::inst::Inst;
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use oxide_parser::Statement;
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impl Emitter {
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pub(crate) fn emit_while_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) -> Result<Option<u32>, String> {
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let Statement::WhileStatement(wh) = stmt else {
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return Ok(None);
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};
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let start_label = ctx.next_label_id();
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let end_label = ctx.next_label_id();
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ctx.labels.set_label_pos(start_label, ctx.insts.len());
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ctx.push_loop(end_label, start_label);
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let n_labeled = ctx.take_pending_loop_labels(end_label, start_label);
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let test_reg = self.emit_expression(&wh.test, ctx)?;
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ctx.inst(Inst::jmp_if_false(test_reg, end_label));
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self.emit_statement(&wh.body, ctx)?;
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ctx.inst(Inst::jmp(start_label));
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ctx.labels.set_label_pos(end_label, ctx.insts.len());
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ctx.pop_label_scopes(n_labeled);
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ctx.pop_loop();
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Ok(None)
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}
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}
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