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|
use anyhow::{anyhow, Context};
use serde_json::Map;
use toml_edit::{DocumentMut, Table};
/// Apply updates from a JSON file to a TOML file while preserving comments in the latter.
#[derive(argh::FromArgs)]
struct Args {
#[argh(positional)]
toml_file: String,
#[argh(positional)]
json_file: String,
/// overwrites the given TOML file rather than printing to stdout
#[argh(switch)]
write: bool,
}
fn main() -> anyhow::Result<()> {
let args: Args = argh::from_env();
let toml = std::fs::read_to_string(&args.toml_file)?;
let json = std::fs::read_to_string(&args.json_file)?;
let mut doc: DocumentMut = toml.parse()?;
let patch: Map<String, serde_json::Value> =
serde_json::from_str(&json).context("failed to parse JSON")?;
apply(&patch, doc.as_table_mut())?;
if args.write {
std::fs::write(args.toml_file, doc.to_string())?;
} else {
print!("{doc}");
}
Ok(())
}
fn apply(patch: &Map<String, serde_json::Value>, table: &mut Table) -> anyhow::Result<()> {
for (key, val) in patch {
match val {
serde_json::Value::Object(map) => {
if !table.contains_key(key) || !matches!(table[key], toml_edit::Item::Table(_)) {
table.insert(key, toml_edit::table());
}
apply(map, table[key].as_table_mut().unwrap())?;
}
other => match json_value_to_toml_value(other)? {
None => {
table.remove(key);
}
Some(new_value) => {
if let Some((_, value)) = table.get_key_value_mut(key) {
*value = new_value.into();
} else {
table.insert(key, new_value.into());
}
}
},
}
}
Ok(())
}
fn json_value_to_toml_value(value: &serde_json::Value) -> anyhow::Result<Option<toml_edit::Value>> {
Ok(match value {
serde_json::Value::Null => None,
serde_json::Value::Bool(bool) => Some((*bool).into()),
serde_json::Value::Number(number) => {
if number.is_u64() {
Some(i64::try_from(number.as_u64().unwrap()).unwrap().into())
} else if number.is_i64() {
Some(number.as_i64().unwrap().into())
} else if number.is_f64() {
Some(number.as_f64().unwrap().into())
} else {
unreachable!();
}
}
serde_json::Value::String(str) => Some(str.into()),
serde_json::Value::Array(vec) => {
let mut new = toml_edit::Array::new();
for value in vec {
match json_value_to_toml_value(value)? {
None => return Err(anyhow!("arrays must not contain null")),
Some(value) => new.push(value),
}
}
Some(new.into())
}
serde_json::Value::Object(_) => unreachable!(),
})
}
#[cfg(test)]
mod tests {
use indoc::indoc;
use serde_json::json;
use toml_edit::DocumentMut;
fn apply(new_value: serde_json::Value, toml: &str) -> anyhow::Result<String> {
let mut doc = toml.parse::<DocumentMut>().unwrap();
super::apply(new_value.as_object().unwrap(), doc.as_table_mut())?;
Ok(doc.to_string())
}
#[test]
fn patch_object() {
assert_eq!(
apply(
json!({"x": {"y": {"foo": true}}}),
indoc! {r#"
[x.y]
# This is x.y.z.
z = 3
# End of x.y section.
"#}
)
.unwrap(),
indoc! {r#"
[x.y]
# This is x.y.z.
z = 3
foo = true
# End of x.y section.
"#}
);
}
#[test]
fn null() {
assert_eq!(apply(json!({"x": null}), "x = 0").unwrap(), "");
}
#[test]
fn object() {
assert_eq!(
apply(json!({"x": {"y": {"z": true}}}), "x = 0").unwrap(),
indoc! {r#"
[x]
[x.y]
z = true
"#}
);
}
#[test]
fn array_may_not_contain_null() {
assert_eq!(
apply(json!({"x": [null]}), "x = 0")
.unwrap_err()
.to_string(),
"arrays must not contain null"
);
}
macro_rules! test_apply {
($name:ident, $json_value:expr, $toml_value:expr) => {
#[test]
fn $name() {
assert_eq!(apply(json!({"x": $json_value}), "x = 0").unwrap(), format!("x = {}\n", $toml_value));
// FUTURE: move these assertions to separate functions once https://github.com/rust-lang/rust/issues/124225 is stable
assert_eq!(
apply(json!({"x": $json_value}), "# before\nx = 0").unwrap(),
format!("# before\nx = {}\n", $toml_value)
);
assert_eq!(
apply(json!({"x": $json_value}), "x = 0\n# after").unwrap(),
format!("x = {}\n# after", $toml_value)
);
}
};
}
test_apply!(bool, true, "true");
test_apply!(u64, 1, "1");
test_apply!(i64, -1, "-1");
test_apply!(f64, 1.0, "1.0");
test_apply!(str, "foo", "\"foo\"");
test_apply!(array, ["foo", "bar"], "[\"foo\", \"bar\"]");
}
|
