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Generate enum-typed setters and constructors for signals with value descriptions #178

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97ce1e0
Generate enum-typed setters and constructors for signals with value d…
felixvanoost Jul 14, 2026
b118c3a
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Jul 14, 2026
b47626a
Resolve clippy errors
felixvanoost Jul 14, 2026
43b5de7
Update variable naming
felixvanoost Jul 18, 2026
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9 changes: 8 additions & 1 deletion fuzz/fuzz_targets/fuzz_target_1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,14 @@ use cantools_messages::{
};

fuzz_target!(|dbc_codegen_bar: can_messages::Bar| {
let dbc_codegen_bar = can_messages::Bar::new(3, 2.0, 4, 5, false).unwrap();
let dbc_codegen_bar = can_messages::Bar::new(
3,
2.0,
can_messages::BarThree::_Other(4),
can_messages::BarFour::_Other(5),
can_messages::BarType::X0off,
)
.unwrap();

println!(
"{} {} {} {} {}",
Expand Down
157 changes: 113 additions & 44 deletions src/lib.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -371,14 +371,14 @@ impl Config<'_> {

self.render_attribute_structs(&mut w, msg, dbc)?;

writeln!(w, "/// Construct new {} from values", msg.name)?;
writeln!(w, "/// Construct new '{}' from values", msg.name)?;
let args = msg
.signals
.iter()
.filter_map(|signal| {
if matches!(signal.multiplexer_indicator, Plain | Multiplexor) {
let field = signal.field_name();
let typ = ValType::from_signal(signal);
let typ = signal_pub_type(dbc, msg, signal);
Some(format!("{field}: {typ}"))
} else {
None
Expand Down Expand Up @@ -417,7 +417,7 @@ impl Config<'_> {
.render_signal(&mut w, signal, dbc, msg)
.with_context(|| format!("write signal impl `{}`", signal.name))?,
Multiplexor => {
self.render_multiplexor_signal(&mut w, signal, msg)?;
self.render_multiplexor_signal(&mut w, signal, dbc, msg)?;
}
MultiplexedSignal(_) | MultiplexorAndMultiplexedSignal(_) => {}
}
Expand Down Expand Up @@ -461,7 +461,7 @@ impl Config<'_> {
self.impl_defmt
.fmt_cfg(&mut *w, |w| render_defmt_impl(w, msg))?;
self.impl_arbitrary
.fmt_cfg(&mut *w, |w| self.render_arbitrary(w, msg))?;
.fmt_cfg(&mut *w, |w| self.render_arbitrary(w, dbc, msg))?;

let enums_for_this_message = dbc.value_descriptions.iter().filter_map(|x| {
if let ValueDescription::Signal {
Expand Down Expand Up @@ -679,7 +679,7 @@ impl Config<'_> {
dbc: &Dbc,
msg: &Message,
) -> Result<()> {
writeln!(w, "/// {}", signal.name)?;
writeln!(w, "/// Get value of '{}'", signal.name)?;
if let Some(comment) = dbc.signal_comment(msg.id, &signal.name) {
writeln!(w, "///")?;
for line in comment.trim().lines() {
Expand Down Expand Up @@ -750,7 +750,7 @@ impl Config<'_> {
writeln!(w)?;
}

writeln!(w, "/// Get raw value of {}", signal.name)?;
writeln!(w, "/// Get raw value of '{}'", signal.name)?;
writeln!(w, "///")?;
writeln!(w, "/// - Start bit: {}", signal.start_bit)?;
writeln!(w, "/// - Signal size: {} bits", signal.size)?;
Expand All @@ -768,15 +768,18 @@ impl Config<'_> {
writeln!(w, "}}")?;
writeln!(w)?;

self.render_set_signal(w, signal, msg)?;
self.render_set_signal(w, signal, dbc, msg)?;

Ok(())
}

fn render_set_signal(&self, w: &mut impl Write, signal: &Signal, msg: &Message) -> Result<()> {
writeln!(w, "/// Set value of {}", signal.name)?;
writeln!(w, "#[inline(always)]")?;

fn render_set_signal(
&self,
w: &mut impl Write,
signal: &Signal,
dbc: &Dbc,
msg: &Message,
) -> Result<()> {
// To avoid accidentally changing the multiplexor value without changing
// the signals accordingly this fn is kept private for multiplexors.
let visibility = if signal.multiplexer_indicator == Multiplexor {
Expand All @@ -787,42 +790,83 @@ impl Config<'_> {

let field = signal.field_name();
let typ = ValType::from_signal(signal);
writeln!(
w,
"{visibility}fn set_{field}(&mut self, value: {typ}) -> Result<(), CanError> {{",
)?;
let param_type = signal_pub_type(dbc, msg, signal);
let is_enum_backed = param_type != typ.to_string();

{
let mut w = PadAdapter::wrap(w);
if is_enum_backed {
writeln!(w, "/// Set value of '{}'", signal.name)?;
writeln!(w, "#[inline(always)]")?;
writeln!(
w,
"{visibility}fn set_{field}(&mut self, value: {param_type}) -> Result<(), CanError> {{",
)?;
{
let mut w = PadAdapter::wrap(w);
writeln!(w, "self.set_{field}_raw({typ}::from(value))")?;
}
writeln!(w, "}}")?;
writeln!(w)?;

if signal.size != 1 {
if let FeatureConfig::Gated(gate) = self.check_ranges {
writeln!(w, r"#[cfg(feature = {gate:?})]")?;
}
writeln!(w, "/// Set raw value of '{}'", signal.name)?;
writeln!(w, "#[inline(always)]")?;
writeln!(
w,
"{visibility}fn set_{field}_raw(&mut self, value: {typ}) -> Result<(), CanError> {{",
)?;
{
let mut w = PadAdapter::wrap(w);
self.render_set_signal_body(&mut w, signal, msg)?;
}
writeln!(w, "}}")?;
writeln!(w)?;
} else {
writeln!(w, "/// Set value of '{}'", signal.name)?;
writeln!(w, "#[inline(always)]")?;
writeln!(
w,
"{visibility}fn set_{field}(&mut self, value: {typ}) -> Result<(), CanError> {{",
)?;
{
let mut w = PadAdapter::wrap(w);
self.render_set_signal_body(&mut w, signal, msg)?;
}
writeln!(w, "}}")?;
writeln!(w)?;
}

if let FeatureConfig::Gated(..) | FeatureConfig::Always = self.check_ranges {
let typ = ValType::from_signal(signal);
let min = signal.min;
let max = signal.max;
writeln!(w, r"if value < {min}_{typ} || {max}_{typ} < value {{")?;
Ok(())
}

{
let mut w = PadAdapter::wrap(&mut w);
let typ = msg.type_name();
writeln!(
w,
r"return Err(CanError::ParameterOutOfRange {{ message_id: {typ}::MESSAGE_ID }});",
)?;
}
fn render_set_signal_body(
&self,
w: &mut impl Write,
signal: &Signal,
msg: &Message,
) -> Result<()> {
if signal.size != 1 {
if let FeatureConfig::Gated(gate) = self.check_ranges {
writeln!(w, r"#[cfg(feature = {gate:?})]")?;
}

if let FeatureConfig::Gated(..) | FeatureConfig::Always = self.check_ranges {
let typ = ValType::from_signal(signal);
let min = signal.min;
let max = signal.max;
writeln!(w, r"if value < {min}_{typ} || {max}_{typ} < value {{")?;

writeln!(w, r"}}")?;
{
let mut w = PadAdapter::wrap(&mut *w);
let typ = msg.type_name();
writeln!(
w,
r"return Err(CanError::ParameterOutOfRange {{ message_id: {typ}::MESSAGE_ID }});",
)?;
}

writeln!(w, r"}}")?;
}
signal_to_payload(&mut w, signal, msg).context("signal to payload")?;
}

writeln!(w, "}}")?;
writeln!(w)?;
signal_to_payload(&mut *w, signal, msg).context("signal to payload")?;

Ok(())
}
Expand All @@ -831,9 +875,10 @@ impl Config<'_> {
&self,
w: &mut impl Write,
signal: &Signal,
dbc: &Dbc,
msg: &Message,
) -> Result<()> {
writeln!(w, "/// Get raw value of {}", signal.name)?;
writeln!(w, "/// Get raw value of '{}'", signal.name)?;
writeln!(w, "///")?;
writeln!(w, "/// - Start bit: {}", signal.start_bit)?;
writeln!(w, "/// - Signal size: {} bits", signal.size)?;
Expand Down Expand Up @@ -900,7 +945,7 @@ impl Config<'_> {
}
writeln!(w, "}}")?;

self.render_set_signal(w, signal, msg)?;
self.render_set_signal(w, signal, dbc, msg)?;

for switch_index in multiplexer_indexes {
render_set_signal_multiplexer(w, signal, msg, switch_index)?;
Expand Down Expand Up @@ -993,7 +1038,7 @@ fn render_set_signal_multiplexer(
msg: &Message,
switch_index: u64,
) -> Result<()> {
writeln!(w, "/// Set value of {}", multiplexor.name)?;
writeln!(w, "/// Set value of '{}'", multiplexor.name)?;
writeln!(w, "#[inline(always)]")?;
writeln!(
w,
Expand Down Expand Up @@ -1064,6 +1109,21 @@ fn le_start_end_bit(signal: &Signal, msg: &Message) -> Result<(u64, u64)> {
Ok((start_bit, end_bit))
}

/// Public type of a signal as seen by `new()` and `set_*`. This is the
/// enum when the signal has one (and isn't the multiplexor selector), otherwise
/// it is the raw primitive type.
fn signal_pub_type(dbc: &Dbc, msg: &Message, signal: &Signal) -> String {
if signal.multiplexer_indicator != Multiplexor
&& dbc
.value_descriptions_for_signal(msg.id, &signal.name)
.is_some()
{
enum_name(msg, signal)
} else {
ValType::from_signal(signal).to_string()
}
}

fn signal_from_payload(w: &mut impl Write, signal: &Signal, msg: &Message) -> Result<()> {
writeln!(w, r"let signal = {};", read_fn(signal, msg)?)?;
writeln!(w)?;
Expand Down Expand Up @@ -1444,7 +1504,7 @@ impl Config<'_> {
Ok(())
}

fn render_arbitrary(&self, w: &mut impl Write, msg: &Message) -> Result<()> {
fn render_arbitrary(&self, w: &mut impl Write, dbc: &Dbc, msg: &Message) -> Result<()> {
writeln!(w, "{ALLOW_LINTS}")?;
self.write_allow_dead_code(w)?;
let typ = msg.type_name();
Expand Down Expand Up @@ -1475,7 +1535,16 @@ impl Config<'_> {

let args: Vec<String> = filtered_signals
.iter()
.map(|signal| signal.field_name())
.map(|signal| {
let field = signal.field_name();
let is_enum_backed = signal_pub_type(dbc, msg, signal)
!= ValType::from_signal(signal).to_string();
if is_enum_backed {
format!("{}::_Other({field})", enum_name(msg, signal))
} else {
field
}
})
.collect();

writeln!(
Expand Down
52 changes: 46 additions & 6 deletions testing/can-messages/tests/all.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,15 +5,15 @@
)]

use can_messages::{
Amet, Bar, BarThree, CanError, Foo, LargerIntsWithOffsets, MsgExtendedId, MultiplexTest,
MultiplexTestMultiplexorIndex, MultiplexTestMultiplexorM0, NegativeFactorTest,
Amet, Bar, BarFour, BarThree, BarType, CanError, Foo, LargerIntsWithOffsets, MsgExtendedId,
MultiplexTest, MultiplexTestMultiplexorIndex, MultiplexTestMultiplexorM0, NegativeFactorTest,
TruncatedBeSignal, TruncatedLeSignal,
};
use embedded_can::{ExtendedId, Id, StandardId};

#[test]
fn check_range_value_error() {
let result = Bar::new(1, 2.0, 3, 4, true);
let result = Bar::new(1, 2.0, BarThree::Onest, BarFour::_Other(4), BarType::X1on);
assert_eq!(
result.unwrap_err(),
CanError::ParameterOutOfRange {
Expand All @@ -24,7 +24,7 @@ fn check_range_value_error() {

#[test]
fn check_range_value_valid() {
let result = Bar::new(1, 2.0, 3, 3, true);
let result = Bar::new(1, 2.0, BarThree::Onest, BarFour::Onest, BarType::X1on);
assert!(result.is_ok());
}

Expand Down Expand Up @@ -141,14 +141,14 @@ fn offset_integers() {

#[test]
fn debug_impl() {
let result = Bar::new(1, 2.0, 3, 3, true).unwrap();
let result = Bar::new(1, 2.0, BarThree::Onest, BarFour::Onest, BarType::X1on).unwrap();
let dbg = format!("{result:?}");
assert_eq!(&dbg, "Bar([5, 94, 0, 64, 0, 0, 0, 0])");
}

#[test]
fn debug_alternative_impl() {
let result = Bar::new(1, 2.0, 3, 3, true).unwrap();
let result = Bar::new(1, 2.0, BarThree::Onest, BarFour::Onest, BarType::X1on).unwrap();
let dbg = format!("{result:#?}");
assert_eq!(
&dbg,
Expand All @@ -162,6 +162,46 @@ fn from_enum_into_raw() {
assert_eq!(raw, 3);
}

#[test]
fn enum_setters_and_getters_are_symmetrical() {
let mut bar = Bar::new(1, 2.0, BarThree::Onest, BarFour::Onest, BarType::X1on).unwrap();

// The setter accepts the enum directly.
bar.set_three(BarThree::Oner).unwrap();
assert_eq!(bar.three(), BarThree::Oner);

// Raw / undescribed values remain settable via the `_Other` variant.
bar.set_three(BarThree::_Other(3)).unwrap();
assert_eq!(bar.three(), BarThree::Onest);

// Out-of-range raw values still produce an error.
assert_eq!(
bar.set_three(BarThree::_Other(8)),
Err(CanError::ParameterOutOfRange {
message_id: Id::Standard(StandardId::new(512).unwrap())
})
);
}

#[test]
fn raw_setter_mirrors_raw_getter() {
let mut bar = Bar::new(1, 2.0, BarThree::Onest, BarFour::Onest, BarType::X1on).unwrap();

bar.set_three_raw(2).unwrap();
assert_eq!(bar.three_raw(), 2);
assert_eq!(bar.three(), BarThree::Oner);

assert_eq!(
bar.set_three_raw(8),
Err(CanError::ParameterOutOfRange {
message_id: Id::Standard(StandardId::new(512).unwrap())
})
);

bar.set_xtype_raw(false).unwrap();
assert_eq!(bar.xtype(), BarType::X0off);
}

#[test]
fn negative_factor() {
assert_eq!(
Expand Down
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