91 lines
3.1 KiB
Rust
91 lines
3.1 KiB
Rust
pub mod parser;
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use parser::{ParsedArgumentResult, ParsedArgumentsIterator};
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use std::collections::{HashMap, HashSet};
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pub fn get_arguments(template: &str) -> Vec<String> {
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let mut char_to_byte: Vec<usize> = template
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.char_indices()
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.map(|(byte_idx, _)| byte_idx)
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.collect();
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char_to_byte.push(template.len());
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ParsedArgumentsIterator::new(template.chars())
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.filter_map(|parsed| {
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if let ParsedArgumentResult::Valid { .. } = parsed.result() {
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let name_range = parsed.chars_range();
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if name_range.start >= 2 {
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let name_start_byte = char_to_byte[name_range.start];
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let name_end_byte = char_to_byte[name_range.end];
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let name = template[name_start_byte..name_end_byte].to_string();
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Some(name)
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} else {
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None
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}
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} else {
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None
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}
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})
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.collect::<HashSet<String>>()
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.into_iter()
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.collect()
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}
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pub fn render_template(template: &str, context: &HashMap<String, String>) -> String {
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// Map char indices to byte indices for slicing.
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let mut char_to_byte: Vec<usize> = template
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.char_indices()
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.map(|(byte_idx, _)| byte_idx)
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.collect();
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char_to_byte.push(template.len());
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let mut out = String::with_capacity(template.len());
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let mut cursor_byte = 0usize;
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for parsed in ParsedArgumentsIterator::new(template.chars()) {
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if let ParsedArgumentResult::Valid { .. } = parsed.result() {
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let name_range = parsed.chars_range();
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// The iterator yields only valid unescaped args without whitespace; the
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// braces are not included in the returned range. For valid args, there
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// must be exactly two braces on each side.
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if name_range.start >= 2 {
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let placeholder_start_char = name_range.start - 2;
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let placeholder_end_char = name_range.end + 2; // exclusive
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let start_byte = char_to_byte[placeholder_start_char];
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let name_start_byte = char_to_byte[name_range.start];
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let name_end_byte = char_to_byte[name_range.end];
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let end_byte = char_to_byte[placeholder_end_char];
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// Append unchanged prefix
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if cursor_byte < start_byte {
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out.push_str(&template[cursor_byte..start_byte]);
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}
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let var_name = &template[name_start_byte..name_end_byte];
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if let Some(value) = context.get(var_name) {
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out.push_str(value);
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} else {
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// If no value provided, keep original placeholder
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out.push_str(&template[start_byte..end_byte]);
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}
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cursor_byte = end_byte;
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}
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}
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}
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// Append suffix
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if cursor_byte < template.len() {
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out.push_str(&template[cursor_byte..]);
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}
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out
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}
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#[cfg(test)]
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#[path = "lib_test.rs"]
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mod tests;
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