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42 lines
1.5 KiB
42 lines
1.5 KiB
5 years ago
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use crate::parse::sexp_expect::{expect_list, expect_string_atom};
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use sexp::Sexp;
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use crate::instr::{Cond, Instr};
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use crate::error::Error;
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use crate::parse::parse_instr::parse_instructions;
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use crate::patches::TryRemove;
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pub fn parse_cond_branch(tok: Sexp) -> Result<(Cond, Vec<Instr>), Error> {
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let mut list = expect_list(Some(tok), false)?;
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let kw = expect_string_atom(list.try_remove(0))?;
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if !kw.ends_with('?') {
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return Err(Error::Parse(format!("Condition must end with '?': {}", kw).into()));
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}
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Ok((parse_cond(&kw)?, parse_instructions(list)?))
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}
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pub fn parse_cond(text: &str) -> Result<Cond, Error> {
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Ok(match text.trim_end_matches('?') {
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"eq" | "=" | "==" => Cond::Equal,
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"ne" | "<>" | "!=" | "≠" => Cond::NotEqual,
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"z" | "0" => Cond::Zero,
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"nz" | "<>0" | "!0" => Cond::NotZero,
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"lt" | "<" => Cond::Less,
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"le" | "<=" | "≤" => Cond::LessOrEqual,
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"gt" => Cond::Greater,
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"ge" | ">=" | "≥" => Cond::GreaterOrEqual,
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"pos" | "+" | ">0" => Cond::Positive,
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"neg" | "-" | "<0" => Cond::Negative,
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"npos" | "!+" | "0-" | "<=0" | "≥0" => Cond::NonPositive,
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"nneg" | "!-" | "0+" | ">=0" | "≤0" => Cond::NonNegative,
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"ov" | "^" => Cond::Overflow,
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"c" => Cond::Carry,
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"nc" | "!c" => Cond::NotCarry,
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"nov" | "!ov" | "!^" => Cond::NotOverflow,
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_ => {
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return Err(Error::Parse(format!("Unknown cond: {}", text).into()));
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}
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})
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}
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