爱特每羊队
57 lines
2.0 KiB
Rust
57 lines
2.0 KiB
Rust
use super::*;
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impl Compiler {
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fn emit_if_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) -> Result<Option<u8>, String> {
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let Statement::IfStatement(ifs) = stmt else {
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return Ok(None);
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};
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let id = ctx.next_label_id();
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let else_label = Label::IfElse(id);
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let end_label = Label::IfEnd(id);
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let test_reg = self.emit_expression(&ifs.test, ctx)?;
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let else_pos = ctx.resolve_label(else_label)?;
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let offset = (else_pos as isize) - (ctx.bytecode.len() as isize);
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let offset = ctx.checked_jump_offset(offset);
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ctx.emit(opcode::encode_jmp_if_false(test_reg, offset));
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let cons_reg = self.emit_statement(&ifs.consequent, ctx)?;
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let result_reg = ctx.alloc_reg();
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if let Some(r) = cons_reg {
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ctx.emit(opcode::encode(OpCode::LOAD_VAR, result_reg, r, 0));
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} else {
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let undef_idx = ctx.add_constant(Constant::Undefined);
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ctx.emit_load_const(result_reg, undef_idx);
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}
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if ifs.alternate.is_some() {
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let end_pos = ctx.resolve_label(end_label)?;
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let offset = (end_pos as isize) - (ctx.bytecode.len() as isize);
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let offset = ctx.checked_jump_offset(offset);
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ctx.emit(opcode::encode_jmp(offset));
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}
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if let Some(alt) = &ifs.alternate {
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let alt_reg = self.emit_statement(alt, ctx)?;
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if let Some(r) = alt_reg {
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ctx.emit(opcode::encode(OpCode::LOAD_VAR, result_reg, r, 0));
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} else {
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let undef_idx = ctx.add_constant(Constant::Undefined);
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ctx.emit_load_const(result_reg, undef_idx);
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}
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}
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Ok(Some(result_reg))
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}
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pub(in crate::emitter) fn emit_control_domain(
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&self, stmt: &Statement, ctx: &mut CompileCtx,
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) -> Result<Option<u8>, String> {
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match stmt {
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Statement::IfStatement(_) => self.emit_if_statement(stmt, ctx),
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_ => Ok(None),
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}
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}
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}
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