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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use crate::{NimbusError, Result};
use serde_json::{value::Value, Map};
#[allow(dead_code)]
pub fn fmt<T: serde::Serialize>(template: &str, context: &T) -> Result<String> {
let obj: Value = serde_json::to_value(context)?;
fmt_with_value(template, &obj)
}
#[allow(dead_code)]
pub fn fmt_with_value(template: &str, value: &Value) -> Result<String> {
if let Value::Object(map) = value {
Ok(fmt_with_map(template, map))
} else {
Err(NimbusError::EvaluationError(
"Can only format json objects".to_string(),
))
}
}
pub fn fmt_with_map(input: &str, context: &Map<String, Value>) -> String {
use unicode_segmentation::UnicodeSegmentation;
let mut output = String::with_capacity(input.len());
let mut iter = input.grapheme_indices(true);
let mut last_index = 0;
// This is exceedingly simple; never refer to this as a parser.
while let Some((index, c)) = iter.next() {
if c == "{" {
let open_index = index;
for (index, c) in iter.by_ref() {
if c == "}" {
let close_index = index;
let field_name = &input[open_index + 1..close_index];
// If we decided to embed JEXL into this templating language,
// this would be the place to put it.
// However, we'd likely want to make this be able to detect balanced braces,
// which this does not.
let replace_string = match context.get(field_name) {
Some(Value::Bool(v)) => v.to_string(),
Some(Value::String(v)) => v.to_string(),
Some(Value::Number(v)) => v.to_string(),
_ => format!("{{{v}}}", v = field_name),
};
output.push_str(&input[last_index..open_index]);
output.push_str(&replace_string);
// +1 skips the closing }
last_index = close_index + 1;
break;
}
}
}
}
output.push_str(&input[last_index..input.len()]);
output
}
#[cfg(test)]
mod unit_tests {
use serde_json::json;
use super::*;
#[test]
fn smoke_tests() {
let c = json!({
"string": "STRING".to_string(),
"number": 42,
"boolean": true,
});
let c = c.as_object().unwrap();
assert_eq!(
fmt_with_map("A {string}, a {number}, a {boolean}.", c),
"A STRING, a 42, a true.".to_string()
);
}
#[test]
fn test_unicode_boundaries() {
let c = json!({
"empty": "".to_string(),
"unicode": "a̐éö̲".to_string(),
"a̐éö̲": "unicode".to_string(),
});
let c = c.as_object().unwrap();
assert_eq!(fmt_with_map("fîré{empty}ƒøüX", c), "fîréƒøüX".to_string());
assert_eq!(fmt_with_map("a̐éö̲{unicode}a̐éö̲", c), "a̐éö̲a̐éö̲a̐éö̲".to_string());
assert_eq!(
fmt_with_map("is this {a̐éö̲}?", c),
"is this unicode?".to_string()
);
}
#[test]
fn test_pathological_cases() {
let c = json!({
"empty": "".to_string(),
});
let c = c.as_object().unwrap();
assert_eq!(
fmt_with_map("A {notthere}.", c),
"A {notthere}.".to_string()
);
assert_eq!(
fmt_with_map("aa { unclosed", c),
"aa { unclosed".to_string()
);
}
}