// Copyright 2020 The Jujutsu Authors//// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at//// https://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License. use std::collections::HashMap;use std::num::ParseIntError;use std::{error, fmt, iter, mem}; use itertools::Itertools as _;use once_cell::sync::Lazy;use pest::iterators::{Pair, Pairs};use pest::pratt_parser::{Assoc, Op, PrattParser};use pest::Parser;use pest_derive::Parser;use thiserror::Error; #[derive(Parser)]#[grammar = "template.pest"]struct TemplateParser; impl Rule {    fn to_symbol(self) -> Option<&'static str> {        match self {            Rule::EOI => None,            Rule::whitespace => None,            Rule::escape => None,            Rule::literal_char => None,            Rule::raw_literal => None,            Rule::literal => None,            Rule::integer_literal => None,            Rule::identifier => None,            Rule::concat_op => Some("++"),            Rule::logical_or_op => Some("||"),            Rule::logical_and_op => Some("&&"),            Rule::logical_not_op => Some("!"),            Rule::negate_op => Some("-"),            Rule::prefix_ops => None,            Rule::infix_ops => None,            Rule::function => None,            Rule::function_arguments => None,            Rule::lambda => None,            Rule::formal_parameters => None,            Rule::primary => None,            Rule::term => None,            Rule::expression => None,            Rule::concat => None,            Rule::template => None,            Rule::program => None,            Rule::function_alias_declaration => None,            Rule::alias_declaration => None,        }    }} pub type TemplateParseResult<T> = Result<T, TemplateParseError>; #[derive(Clone, Debug)]pub struct TemplateParseError {    kind: TemplateParseErrorKind,    pest_error: Box<pest::error::Error<Rule>>,    origin: Option<Box<TemplateParseError>>,} #[derive(Clone, Debug, Eq, Error, PartialEq)]pub enum TemplateParseErrorKind {    #[error("Syntax error")]    SyntaxError,    #[error("Invalid integer literal")]    ParseIntError(#[source] ParseIntError),    #[error(r#"Keyword "{name}" doesn't exist"#)]    NoSuchKeyword {        name: String,        candidates: Vec<String>,    },    #[error(r#"Function "{name}" doesn't exist"#)]    NoSuchFunction {        name: String,        candidates: Vec<String>,    },    #[error(r#"Method "{name}" doesn't exist for type "{type_name}""#)]    NoSuchMethod {        type_name: String,        name: String,        candidates: Vec<String>,    },    #[error(r#"Function "{name}": {message}"#)]    InvalidArguments { name: String, message: String },    #[error("Redefinition of function parameter")]    RedefinedFunctionParameter,    #[error("{0}")]    UnexpectedExpression(String),    #[error(r#"Alias "{0}" cannot be expanded"#)]    BadAliasExpansion(String),    #[error(r#"Alias "{0}" expanded recursively"#)]    RecursiveAlias(String),} impl TemplateParseError {    pub fn with_span(kind: TemplateParseErrorKind, span: pest::Span<'_>) -> Self {        let message = iter::successors(Some(&kind as &dyn error::Error), |e| e.source()).join(": ");        let pest_error = Box::new(pest::error::Error::new_from_span(            pest::error::ErrorVariant::CustomError { message },            span,        ));        TemplateParseError {            kind,            pest_error,            origin: None,        }    }     pub fn with_span_and_origin(        kind: TemplateParseErrorKind,        span: pest::Span<'_>,        origin: Self,    ) -> Self {        let message = iter::successors(Some(&kind as &dyn error::Error), |e| e.source()).join(": ");        let pest_error = Box::new(pest::error::Error::new_from_span(            pest::error::ErrorVariant::CustomError { message },            span,        ));        TemplateParseError {            kind,            pest_error,            origin: Some(Box::new(origin)),        }    }     // TODO: migrate callers to something like lookup_method()    pub(crate) fn no_such_function(function: &FunctionCallNode) -> Self {        TemplateParseError::with_span(            TemplateParseErrorKind::NoSuchFunction {                name: function.name.to_owned(),                candidates: vec![],            },            function.name_span,        )    }     // TODO: migrate all callers to table-based lookup_method()    pub(crate) fn no_such_method(        type_name: impl Into<String>,        function: &FunctionCallNode,    ) -> Self {        TemplateParseError::with_span(            TemplateParseErrorKind::NoSuchMethod {                type_name: type_name.into(),                name: function.name.to_owned(),                candidates: vec![],            },            function.name_span,        )    }     pub fn invalid_arguments(function: &FunctionCallNode, message: impl Into<String>) -> Self {        TemplateParseError::with_span(            TemplateParseErrorKind::InvalidArguments {                name: function.name.to_owned(),                message: message.into(),            },            function.args_span,        )    }     pub fn expected_type(type_name: &str, span: pest::Span<'_>) -> Self {        let message = format!(r#"Expected expression of type "{type_name}""#);        TemplateParseError::unexpected_expression(message, span)    }     pub fn unexpected_expression(message: impl Into<String>, span: pest::Span<'_>) -> Self {        TemplateParseError::with_span(            TemplateParseErrorKind::UnexpectedExpression(message.into()),            span,        )    }     pub fn within_alias_expansion(self, id: TemplateAliasId<'_>, span: pest::Span<'_>) -> Self {        TemplateParseError::with_span_and_origin(            TemplateParseErrorKind::BadAliasExpansion(id.to_string()),            span,            self,        )    }     /// If this is a `NoSuchKeyword` error, expands the candidates list with the    /// given `other_keywords`.    pub fn extend_keyword_candidates<I>(mut self, other_keywords: I) -> Self    where        I: IntoIterator,        I::Item: AsRef<str>,    {        if let TemplateParseErrorKind::NoSuchKeyword { name, candidates } = &mut self.kind {            let other_candidates = collect_similar(name, other_keywords);            *candidates = itertools::merge(mem::take(candidates), other_candidates)                .dedup()                .collect();        }        self    }     /// If this is a `NoSuchFunction` error, expands the candidates list with    /// the given `other_functions`.    pub fn extend_function_candidates<I>(mut self, other_functions: I) -> Self    where        I: IntoIterator,        I::Item: AsRef<str>,    {        if let TemplateParseErrorKind::NoSuchFunction { name, candidates } = &mut self.kind {            let other_candidates = collect_similar(name, other_functions);            *candidates = itertools::merge(mem::take(candidates), other_candidates)                .dedup()                .collect();        }        self    }     /// Expands keyword/function candidates with the given aliases.    pub fn extend_alias_candidates(self, aliases_map: &TemplateAliasesMap) -> Self {        self.extend_keyword_candidates(aliases_map.symbol_aliases.keys())            .extend_function_candidates(aliases_map.function_aliases.keys())    }     pub fn kind(&self) -> &TemplateParseErrorKind {        &self.kind    }     /// Original parsing error which typically occurred in an alias expression.    pub fn origin(&self) -> Option<&Self> {        self.origin.as_deref()    }} impl From<pest::error::Error<Rule>> for TemplateParseError {    fn from(err: pest::error::Error<Rule>) -> Self {        TemplateParseError {            kind: TemplateParseErrorKind::SyntaxError,            pest_error: Box::new(rename_rules_in_pest_error(err)),            origin: None,        }    }} impl fmt::Display for TemplateParseError {    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {        self.pest_error.fmt(f)    }} impl error::Error for TemplateParseError {    fn source(&self) -> Option<&(dyn error::Error + 'static)> {        if let Some(e) = self.origin() {            return Some(e as &dyn error::Error);        }        match &self.kind {            // SyntaxError is a wrapper for pest::error::Error.            TemplateParseErrorKind::SyntaxError => Some(&self.pest_error as &dyn error::Error),            // Otherwise the kind represents this error.            e => e.source(),        }    }} fn rename_rules_in_pest_error(err: pest::error::Error<Rule>) -> pest::error::Error<Rule> {    err.renamed_rules(|rule| {        rule.to_symbol()            .map(|sym| format!("`{sym}`"))            .unwrap_or_else(|| format!("<{rule:?}>"))    })} /// AST node without type or name checking.#[derive(Clone, Debug, PartialEq)]pub struct ExpressionNode<'i> {    pub kind: ExpressionKind<'i>,    pub span: pest::Span<'i>,} impl<'i> ExpressionNode<'i> {    fn new(kind: ExpressionKind<'i>, span: pest::Span<'i>) -> Self {        ExpressionNode { kind, span }    }} #[derive(Clone, Debug, PartialEq)]pub enum ExpressionKind<'i> {    Identifier(&'i str),    Boolean(bool),    Integer(i64),    String(String),    Unary(UnaryOp, Box<ExpressionNode<'i>>),    Binary(BinaryOp, Box<ExpressionNode<'i>>, Box<ExpressionNode<'i>>),    Concat(Vec<ExpressionNode<'i>>),    FunctionCall(FunctionCallNode<'i>),    MethodCall(MethodCallNode<'i>),    Lambda(LambdaNode<'i>),    /// Identity node to preserve the span in the source template text.    AliasExpanded(TemplateAliasId<'i>, Box<ExpressionNode<'i>>),} #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]pub enum UnaryOp {    /// `!`    LogicalNot,    /// `-`    Negate,} #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]pub enum BinaryOp {    /// `||`    LogicalOr,    /// `&&`    LogicalAnd,} #[derive(Clone, Debug, PartialEq)]pub struct FunctionCallNode<'i> {    pub name: &'i str,    pub name_span: pest::Span<'i>,    pub args: Vec<ExpressionNode<'i>>,    pub args_span: pest::Span<'i>,} #[derive(Clone, Debug, PartialEq)]pub struct MethodCallNode<'i> {    pub object: Box<ExpressionNode<'i>>,    pub function: FunctionCallNode<'i>,} #[derive(Clone, Debug, PartialEq)]pub struct LambdaNode<'i> {    pub params: Vec<&'i str>,    pub params_span: pest::Span<'i>,    pub body: Box<ExpressionNode<'i>>,} fn parse_identifier_or_literal(pair: Pair<Rule>) -> ExpressionKind {    assert_eq!(pair.as_rule(), Rule::identifier);    match pair.as_str() {        "false" => ExpressionKind::Boolean(false),        "true" => ExpressionKind::Boolean(true),        name => ExpressionKind::Identifier(name),    }} fn parse_identifier_name(pair: Pair<Rule>) -> TemplateParseResult<&str> {    let span = pair.as_span();    if let ExpressionKind::Identifier(name) = parse_identifier_or_literal(pair) {        Ok(name)    } else {        Err(TemplateParseError::unexpected_expression(            "Expected identifier",            span,        ))    }} fn parse_string_literal(pair: Pair<Rule>) -> String {    assert_eq!(pair.as_rule(), Rule::literal);    let mut result = String::new();    for part in pair.into_inner() {        match part.as_rule() {            Rule::raw_literal => {                result.push_str(part.as_str());            }            Rule::escape => match &part.as_str()[1..] {                "\"" => result.push('"'),                "\\" => result.push('\\'),                "t" => result.push('\t'),                "r" => result.push('\r'),                "n" => result.push('\n'),                "0" => result.push('\0'),                char => panic!("invalid escape: \\{char:?}"),            },            _ => panic!("unexpected part of string: {part:?}"),        }    }    result} fn parse_formal_parameters(params_pair: Pair<Rule>) -> TemplateParseResult<Vec<&str>> {    assert_eq!(params_pair.as_rule(), Rule::formal_parameters);    let params_span = params_pair.as_span();    let params: Vec<_> = params_pair        .into_inner()        .map(parse_identifier_name)        .try_collect()?;    if params.iter().all_unique() {        Ok(params)    } else {        Err(TemplateParseError::with_span(            TemplateParseErrorKind::RedefinedFunctionParameter,            params_span,        ))    }} fn parse_function_call_node(pair: Pair<Rule>) -> TemplateParseResult<FunctionCallNode> {    assert_eq!(pair.as_rule(), Rule::function);    let mut inner = pair.into_inner();    let name_pair = inner.next().unwrap();    let name_span = name_pair.as_span();    let args_pair = inner.next().unwrap();    let args_span = args_pair.as_span();    assert_eq!(args_pair.as_rule(), Rule::function_arguments);    let name = parse_identifier_name(name_pair)?;    let args = args_pair        .into_inner()        .map(parse_template_node)        .try_collect()?;    Ok(FunctionCallNode {        name,        name_span,        args,        args_span,    })} fn parse_lambda_node(pair: Pair<Rule>) -> TemplateParseResult<LambdaNode> {    assert_eq!(pair.as_rule(), Rule::lambda);    let mut inner = pair.into_inner();    let params_pair = inner.next().unwrap();    let params_span = params_pair.as_span();    let body_pair = inner.next().unwrap();    let params = parse_formal_parameters(params_pair)?;    let body = parse_template_node(body_pair)?;    Ok(LambdaNode {        params,        params_span,        body: Box::new(body),    })} fn parse_term_node(pair: Pair<Rule>) -> TemplateParseResult<ExpressionNode> {    assert_eq!(pair.as_rule(), Rule::term);    let mut inner = pair.into_inner();    let expr = inner.next().unwrap();    let span = expr.as_span();    let primary = match expr.as_rule() {        Rule::literal => {            let text = parse_string_literal(expr);            ExpressionNode::new(ExpressionKind::String(text), span)        }        Rule::integer_literal => {            let value = expr.as_str().parse().map_err(|err| {                TemplateParseError::with_span(TemplateParseErrorKind::ParseIntError(err), span)            })?;            ExpressionNode::new(ExpressionKind::Integer(value), span)        }        Rule::identifier => ExpressionNode::new(parse_identifier_or_literal(expr), span),        Rule::function => {            let function = parse_function_call_node(expr)?;            ExpressionNode::new(ExpressionKind::FunctionCall(function), span)        }        Rule::lambda => {            let lambda = parse_lambda_node(expr)?;            ExpressionNode::new(ExpressionKind::Lambda(lambda), span)        }        Rule::template => parse_template_node(expr)?,        other => panic!("unexpected term: {other:?}"),    };    inner.try_fold(primary, |object, chain| {        assert_eq!(chain.as_rule(), Rule::function);        let span = object.span.start_pos().span(&chain.as_span().end_pos());        let method = MethodCallNode {            object: Box::new(object),            function: parse_function_call_node(chain)?,        };        Ok(ExpressionNode::new(            ExpressionKind::MethodCall(method),            span,        ))    })} fn parse_expression_node(pair: Pair<Rule>) -> TemplateParseResult<ExpressionNode> {    assert_eq!(pair.as_rule(), Rule::expression);    static PRATT: Lazy<PrattParser<Rule>> = Lazy::new(|| {        PrattParser::new()            .op(Op::infix(Rule::logical_or_op, Assoc::Left))            .op(Op::infix(Rule::logical_and_op, Assoc::Left))            .op(Op::prefix(Rule::logical_not_op) | Op::prefix(Rule::negate_op))    });    PRATT        .map_primary(parse_term_node)        .map_prefix(|op, rhs| {            let op_kind = match op.as_rule() {                Rule::logical_not_op => UnaryOp::LogicalNot,                Rule::negate_op => UnaryOp::Negate,                r => panic!("unexpected prefix operator rule {r:?}"),

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