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use super::token::TokenString;
pub(crate) enum ConditionalLine {
/// spelled "ifeq"
IfEqual(TokenString, TokenString),
/// spelled "ifneq"
IfNotEqual(TokenString, TokenString),
/// spelled "ifdef"
IfDefined(String),
/// spelled "ifndef"
IfNotDefined(String),
/// spelled "else"
Else,
/// spelled "else condition"
ElseIf(Box<ConditionalLine>),
/// spelled "endif"
EndIf,
}
pub(crate) enum ConditionalState {
/// we saw a conditional, the condition was true, we're executing now
/// and if we hit an else we will start SkippingUntilEndIf
Executing,
/// we saw a conditional, the condition was false, we're ignoring now
/// and if we hit an else we'll start executing
/// (or if it's an else if we'll check the condition)
SkippingUntilElseOrEndIf,
/// we saw a conditional, the condition was true, we executed, and now we hit an else
/// so we don't need to stop and evaluate new conditions, because we straight up do
/// not care
SkippingUntilEndIf,
}
impl ConditionalState {
pub(crate) const fn skipping(&self) -> bool {
match self {
Self::Executing => false,
Self::SkippingUntilElseOrEndIf | Self::SkippingUntilEndIf => true,
}
}
}
pub(crate) enum ConditionalStateAction {
Push(ConditionalState),
Replace(ConditionalState),
Pop,
}
impl ConditionalStateAction {
pub(crate) fn apply_to(self, stack: &mut Vec<ConditionalState>) {
match self {
Self::Push(state) => stack.push(state),
Self::Replace(state) => match stack.last_mut() {
Some(x) => *x = state,
None => panic!("applying Replace on an empty condition stack"),
},
Self::Pop => {
stack.pop();
}
}
}
}
fn decode_condition_args(line_body: &str) -> Option<(TokenString, TokenString)> {
let tokens: TokenString = line_body.parse().ok()?;
let (mut arg1, mut arg2) = if tokens.starts_with("(") && tokens.ends_with(")") {
let mut tokens = tokens;
tokens.strip_prefix("(");
tokens.strip_suffix(")");
tokens.split_once(',')?
} else {
// TODO see if i really need to implement potentially-mixed-quoted args
return None;
};
arg1.trim_end();
arg2.trim_start();
Some((arg1, arg2))
}
impl ConditionalLine {
pub(crate) fn from(line: &str, expand_macro: impl Fn(&TokenString) -> String) -> Option<Self> {
if let Some(line) = line.strip_prefix("ifeq ") {
let (arg1, arg2) = decode_condition_args(line)?;
Some(Self::IfEqual(arg1, arg2))
} else if let Some(line) = line.strip_prefix("ifneq ") {
let (arg1, arg2) = decode_condition_args(line)?;
Some(Self::IfNotEqual(arg1, arg2))
} else if let Some(line) = line.strip_prefix("ifdef ") {
Some(Self::IfDefined(expand_macro(&line.parse().ok()?)))
} else if let Some(line) = line.strip_prefix("ifndef ") {
Some(Self::IfNotDefined(expand_macro(&line.parse().ok()?)))
} else if line == "else" {
Some(Self::Else)
} else if let Some(line) = line.strip_prefix("else ") {
let sub_condition = Self::from(line, expand_macro)?;
Some(Self::ElseIf(Box::new(sub_condition)))
} else if line == "endif" {
Some(Self::EndIf)
} else {
None
}
}
pub(crate) fn action(
&self,
current_state: Option<&ConditionalState>,
is_macro_defined: impl Fn(&str) -> bool,
expand_macro: impl Fn(&TokenString) -> String,
) -> ConditionalStateAction {
use ConditionalState as State;
use ConditionalStateAction as Action;
match self {
Self::IfEqual(arg1, arg2) => {
let arg1 = expand_macro(arg1);
let arg2 = expand_macro(arg2);
if arg1 == arg2 {
Action::Push(State::Executing)
} else {
Action::Push(State::SkippingUntilElseOrEndIf)
}
}
Self::IfNotEqual(arg1, arg2) => {
let arg1 = expand_macro(arg1);
let arg2 = expand_macro(arg2);
if arg1 == arg2 {
Action::Push(State::SkippingUntilElseOrEndIf)
} else {
Action::Push(State::Executing)
}
}
Self::IfDefined(name) => {
if is_macro_defined(name) {
Action::Push(State::Executing)
} else {
Action::Push(State::SkippingUntilElseOrEndIf)
}
}
Self::IfNotDefined(name) => {
if is_macro_defined(name) {
Action::Push(State::SkippingUntilElseOrEndIf)
} else {
Action::Push(State::Executing)
}
}
Self::Else => Action::Replace(match current_state {
Some(State::Executing) | Some(State::SkippingUntilEndIf) => {
State::SkippingUntilEndIf
}
Some(State::SkippingUntilElseOrEndIf) => State::Executing,
None => panic!("got an Else but not in a conditional"),
}),
Self::ElseIf(inner_condition) => match current_state {
Some(State::Executing) | Some(State::SkippingUntilEndIf) => {
Action::Replace(State::SkippingUntilEndIf)
}
Some(State::SkippingUntilElseOrEndIf) => {
inner_condition.action(current_state, is_macro_defined, expand_macro)
}
None => panic!("got an ElseIf but not in a conditional"),
},
Self::EndIf => Action::Pop,
}
}
}
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