mirror of https://github.com/sigoden/aichat
feat: custom REPL prompt (#283)
sigoden
5 months ago
committed by
GitHub
parent
89fefb4d1a
commit
1c9ca1b002
@ -0,0 +1,155 @@
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use std::collections::HashMap;
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/// Render REPL prompt
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///
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/// The template comprises plain text and `{...}`.
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///
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/// The syntax of `{...}`:
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/// - `{var}` - When `var` has a value, replace `var` with the value and eval `template`
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/// - `{?var <template>}` - Eval `template` when `var` is evaluated as true
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/// - `{!var <template>}` - Eval `template` when `var` is evaluated as false
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pub fn render_prompt(template: &str, variables: &HashMap<&str, String>) -> String {
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let exprs = parse_template(template);
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eval_exprs(&exprs, variables)
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}
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fn parse_template(template: &str) -> Vec<Expr> {
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let chars: Vec<char> = template.chars().collect();
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let mut exprs = vec![];
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let mut current = vec![];
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let mut balances = vec![];
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for ch in chars.iter().cloned() {
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if !balances.is_empty() {
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if ch == '}' {
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balances.pop();
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if balances.is_empty() {
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if !current.is_empty() {
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let block = parse_block(&mut current);
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exprs.push(block)
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}
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} else {
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current.push(ch);
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}
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} else if ch == '{' {
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balances.push(ch);
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current.push(ch);
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} else {
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current.push(ch);
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}
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} else if ch == '{' {
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balances.push(ch);
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add_text(&mut exprs, &mut current);
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} else {
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current.push(ch)
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}
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}
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add_text(&mut exprs, &mut current);
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exprs
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}
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fn parse_block(current: &mut Vec<char>) -> Expr {
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let value: String = current.drain(..).collect();
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match value.split_once(' ') {
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Some((name, tail)) => {
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if let Some(name) = name.strip_prefix('?') {
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let block_exprs = parse_template(tail);
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Expr::Block(BlockType::Yes, name.to_string(), block_exprs)
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} else if let Some(name) = name.strip_prefix('!') {
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let block_exprs = parse_template(tail);
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Expr::Block(BlockType::No, name.to_string(), block_exprs)
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} else {
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Expr::Text(format!("{{{value}}}"))
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}
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}
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None => Expr::Variable(value),
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}
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}
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fn eval_exprs(exprs: &[Expr], variables: &HashMap<&str, String>) -> String {
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let mut output = String::new();
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for part in exprs {
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match part {
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Expr::Text(text) => output.push_str(text),
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Expr::Variable(variable) => {
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let value = variables
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.get(variable.as_str())
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.cloned()
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.unwrap_or_default();
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output.push_str(&value);
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}
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Expr::Block(typ, variable, block_exprs) => {
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let value = variables
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.get(variable.as_str())
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.cloned()
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.unwrap_or_default();
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match typ {
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BlockType::Yes => {
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if truly(&value) {
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let block_output = eval_exprs(block_exprs, variables);
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output.push_str(&block_output)
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}
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}
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BlockType::No => {
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if !truly(&value) {
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let block_output = eval_exprs(block_exprs, variables);
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output.push_str(&block_output)
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}
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}
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}
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}
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}
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}
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output
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}
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fn add_text(exprs: &mut Vec<Expr>, current: &mut Vec<char>) {
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if current.is_empty() {
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return;
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}
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let value: String = current.drain(..).collect();
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exprs.push(Expr::Text(value));
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}
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fn truly(value: &str) -> bool {
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!(value.is_empty() || value == "0" || value == "false")
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}
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#[derive(Debug)]
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enum Expr {
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Text(String),
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Variable(String),
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Block(BlockType, String, Vec<Expr>),
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}
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#[derive(Debug)]
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enum BlockType {
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Yes,
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No,
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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macro_rules! assert_render {
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($template:expr, [$(($key:literal, $value:literal),)*], $expect:literal) => {
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let data = HashMap::from([
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$(($key, $value.into()),)*
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]);
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assert_eq!(render_prompt($template, &data), $expect);
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};
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}
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#[test]
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fn test_render() {
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let prompt = "{?session {session}{?role /}}{role}{?session )}{!session >}";
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assert_render!(prompt, [], ">");
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assert_render!(prompt, [("role", "coder"),], "coder>");
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assert_render!(prompt, [("session", "temp"),], "temp)");
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assert_render!(
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prompt,
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[("session", "temp"), ("role", "coder"),],
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"temp/coder)"
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);
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}
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}
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