211 lines
8.5 KiB
Rust
211 lines
8.5 KiB
Rust
use itertools::Itertools;
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use crate::{
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ast::{BinOp, SimplExpr, Span, UnaryOp},
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dynval::{ConversionError, DynVal},
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};
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use std::collections::HashMap;
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#[derive(Debug, thiserror::Error)]
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pub enum EvalError {
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#[error("Invalid regex: {0}")]
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InvalidRegex(#[from] regex::Error),
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#[error("got unresolved variable `{0}`")]
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UnresolvedVariable(VarName),
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#[error("Type error: {0}")]
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ConversionError(#[from] ConversionError),
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#[error("Incorrect number of arguments given to function: {0}")]
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WrongArgCount(String),
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#[error("Unknown function {0}")]
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UnknownFunction(String),
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#[error("Unknown variable {0}")]
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UnknownVariable(String),
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#[error("Unable to index into value {0}")]
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CannotIndex(String),
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#[error("{1}")]
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Spanned(Span, Box<EvalError>),
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}
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impl EvalError {
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pub fn span(&self) -> Option<Span> {
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match self {
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EvalError::Spanned(span, _) => Some(*span),
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EvalError::ConversionError(err) => err.span(),
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_ => None,
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}
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}
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pub fn at(self, span: Span) -> Self {
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Self::Spanned(span, Box::new(self))
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}
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}
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type VarName = String;
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pub trait FunctionSource {
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type Err;
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fn run_fn(&self, name: &str, args: &Vec<DynVal>) -> Result<DynVal, Self::Err>;
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}
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impl SimplExpr {
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pub fn map_terminals_into(self, f: impl Fn(Self) -> Self) -> Self {
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use SimplExpr::*;
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match self {
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BinOp(span, box a, op, box b) => BinOp(span, box f(a), op, box f(b)),
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UnaryOp(span, op, box a) => UnaryOp(span, op, box f(a)),
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IfElse(span, box a, box b, box c) => IfElse(span, box f(a), box f(b), box f(c)),
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JsonAccess(span, box a, box b) => JsonAccess(span, box f(a), box f(b)),
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FunctionCall(span, name, args) => FunctionCall(span, name, args.into_iter().map(f).collect()),
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other => f(other),
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}
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}
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/// resolve variable references in the expression. Fails if a variable cannot be resolved.
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pub fn resolve_refs(self, variables: &HashMap<VarName, DynVal>) -> Result<Self, EvalError> {
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use SimplExpr::*;
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match self {
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// Literal(x) => Ok(Literal(AttrValue::from_primitive(x.resolve_fully(&variables)?))),
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Literal(span, x) => Ok(Literal(span, x)),
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BinOp(span, box a, op, box b) => Ok(BinOp(span, box a.resolve_refs(variables)?, op, box b.resolve_refs(variables)?)),
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UnaryOp(span, op, box x) => Ok(UnaryOp(span, op, box x.resolve_refs(variables)?)),
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IfElse(span, box a, box b, box c) => {
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Ok(IfElse(span, box a.resolve_refs(variables)?, box b.resolve_refs(variables)?, box c.resolve_refs(variables)?))
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}
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JsonAccess(span, box a, box b) => {
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Ok(JsonAccess(span, box a.resolve_refs(variables)?, box b.resolve_refs(variables)?))
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}
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FunctionCall(span, function_name, args) => Ok(FunctionCall(
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span,
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function_name,
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args.into_iter().map(|a| a.resolve_refs(variables)).collect::<Result<_, EvalError>>()?,
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)),
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VarRef(span, ref name) => match variables.get(name) {
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Some(value) => Ok(Literal(span, value.clone())),
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None => Err(EvalError::UnknownVariable(name.to_string()).at(span)),
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},
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}
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}
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pub fn var_refs(&self) -> Vec<&String> {
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use SimplExpr::*;
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match self {
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Literal(..) => Vec::new(),
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VarRef(_, name) => vec![name],
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BinOp(_, box a, _, box b) | JsonAccess(_, box a, box b) => {
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let mut refs = a.var_refs();
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refs.append(&mut b.var_refs());
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refs
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}
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UnaryOp(_, _, box x) => x.var_refs(),
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IfElse(_, box a, box b, box c) => {
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let mut refs = a.var_refs();
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refs.append(&mut b.var_refs());
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refs.append(&mut c.var_refs());
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refs
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}
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FunctionCall(_, _, args) => args.iter().flat_map(|a| a.var_refs()).collect_vec(),
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}
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}
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pub fn eval(self, values: &HashMap<VarName, DynVal>) -> Result<DynVal, EvalError> {
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let span = self.span();
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let value = match self {
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SimplExpr::Literal(_, x) => Ok(x),
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SimplExpr::VarRef(span, ref name) => {
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Ok(values.get(name).cloned().ok_or_else(|| EvalError::UnresolvedVariable(name.to_string()).at(span))?.at(span))
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}
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SimplExpr::BinOp(_, a, op, b) => {
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let a = a.eval(values)?;
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let b = b.eval(values)?;
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Ok(match op {
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BinOp::Equals => DynVal::from(a == b),
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BinOp::NotEquals => DynVal::from(a != b),
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BinOp::And => DynVal::from(a.as_bool()? && b.as_bool()?),
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BinOp::Or => DynVal::from(a.as_bool()? || b.as_bool()?),
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BinOp::Plus => match a.as_f64() {
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Ok(num) => DynVal::from(num + b.as_f64()?),
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Err(_) => DynVal::from(format!("{}{}", a.as_string()?, b.as_string()?)),
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},
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BinOp::Minus => DynVal::from(a.as_f64()? - b.as_f64()?),
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BinOp::Times => DynVal::from(a.as_f64()? * b.as_f64()?),
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BinOp::Div => DynVal::from(a.as_f64()? / b.as_f64()?),
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BinOp::Mod => DynVal::from(a.as_f64()? % b.as_f64()?),
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BinOp::GT => DynVal::from(a.as_f64()? > b.as_f64()?),
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BinOp::LT => DynVal::from(a.as_f64()? < b.as_f64()?),
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BinOp::Elvis => DynVal::from(if a.0.is_empty() { b } else { a }),
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BinOp::RegexMatch => {
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let regex = regex::Regex::new(&b.as_string()?)?;
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DynVal::from(regex.is_match(&a.as_string()?))
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}
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})
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}
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SimplExpr::UnaryOp(_, op, a) => {
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let a = a.eval(values)?;
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Ok(match op {
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UnaryOp::Not => DynVal::from(!a.as_bool()?),
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})
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}
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SimplExpr::IfElse(_, cond, yes, no) => {
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if cond.eval(values)?.as_bool()? {
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yes.eval(values)
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} else {
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no.eval(values)
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}
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}
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SimplExpr::JsonAccess(span, val, index) => {
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let val = val.eval(values)?;
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let index = index.eval(values)?;
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match val.as_json_value()? {
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serde_json::Value::Array(val) => {
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let index = index.as_i32()?;
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let indexed_value = val.get(index as usize).unwrap_or(&serde_json::Value::Null);
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Ok(DynVal::from(indexed_value))
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}
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serde_json::Value::Object(val) => {
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let indexed_value = val
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.get(&index.as_string()?)
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.or_else(|| val.get(&index.as_i32().ok()?.to_string()))
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.unwrap_or(&serde_json::Value::Null);
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Ok(DynVal::from(indexed_value))
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}
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_ => Err(EvalError::CannotIndex(format!("{}", val)).at(span)),
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}
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}
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SimplExpr::FunctionCall(span, function_name, args) => {
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let args = args.into_iter().map(|a| a.eval(values)).collect::<Result<_, EvalError>>()?;
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call_expr_function(&function_name, args).map_err(|e| e.at(span))
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}
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};
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Ok(value?.at(span))
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}
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}
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fn call_expr_function(name: &str, args: Vec<DynVal>) -> Result<DynVal, EvalError> {
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match name {
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"round" => match args.as_slice() {
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[num, digits] => {
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let num = num.as_f64()?;
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let digits = digits.as_i32()?;
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Ok(DynVal::from(format!("{:.1$}", num, digits as usize)))
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}
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_ => Err(EvalError::WrongArgCount(name.to_string())),
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},
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"replace" => match args.as_slice() {
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[string, pattern, replacement] => {
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let string = string.as_string()?;
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let pattern = regex::Regex::new(&pattern.as_string()?)?;
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let replacement = replacement.as_string()?;
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Ok(DynVal::from(pattern.replace_all(&string, replacement.replace("$", "$$").replace("\\", "$")).into_owned()))
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}
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_ => Err(EvalError::WrongArgCount(name.to_string())),
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},
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_ => Err(EvalError::UnknownFunction(name.to_string())),
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}
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}
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