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|
//! This file contains code for parsing SSR rules, which look something like `foo($a) ==>> bar($b)`.
//! We first split everything before and after the separator `==>>`. Next, both the search pattern
//! and the replacement template get tokenized by the Rust tokenizer. Tokens are then searched for
//! placeholders, which start with `$`. For replacement templates, this is the final form. For
//! search patterns, we go further and parse the pattern as each kind of thing that we can match.
//! e.g. expressions, type references etc.
use crate::errors::bail;
use crate::{SsrError, SsrPattern, SsrRule};
use ra_syntax::{ast, AstNode, SmolStr, SyntaxKind, T};
use rustc_hash::{FxHashMap, FxHashSet};
use std::str::FromStr;
#[derive(Clone, Debug)]
pub(crate) struct SsrTemplate {
pub(crate) tokens: Vec<PatternElement>,
}
#[derive(Debug)]
pub(crate) struct RawSearchPattern {
tokens: Vec<PatternElement>,
}
// Part of a search or replace pattern.
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) enum PatternElement {
Token(Token),
Placeholder(Placeholder),
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) struct Placeholder {
/// The name of this placeholder. e.g. for "$a", this would be "a"
pub(crate) ident: SmolStr,
/// A unique name used in place of this placeholder when we parse the pattern as Rust code.
stand_in_name: String,
pub(crate) constraints: Vec<Constraint>,
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) enum Constraint {
Kind(NodeKind),
Not(Box<Constraint>),
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub(crate) enum NodeKind {
Literal,
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) struct Token {
kind: SyntaxKind,
pub(crate) text: SmolStr,
}
impl FromStr for SsrRule {
type Err = SsrError;
fn from_str(query: &str) -> Result<SsrRule, SsrError> {
let mut it = query.split("==>>");
let pattern = it.next().expect("at least empty string").trim();
let template = it
.next()
.ok_or_else(|| SsrError("Cannot find delimiter `==>>`".into()))?
.trim()
.to_string();
if it.next().is_some() {
return Err(SsrError("More than one delimiter found".into()));
}
let rule = SsrRule { pattern: pattern.parse()?, template: template.parse()? };
validate_rule(&rule)?;
Ok(rule)
}
}
impl FromStr for RawSearchPattern {
type Err = SsrError;
fn from_str(pattern_str: &str) -> Result<RawSearchPattern, SsrError> {
Ok(RawSearchPattern { tokens: parse_pattern(pattern_str)? })
}
}
impl RawSearchPattern {
/// Returns this search pattern as Rust source code that we can feed to the Rust parser.
fn as_rust_code(&self) -> String {
let mut res = String::new();
for t in &self.tokens {
res.push_str(match t {
PatternElement::Token(token) => token.text.as_str(),
PatternElement::Placeholder(placeholder) => placeholder.stand_in_name.as_str(),
});
}
res
}
fn placeholders_by_stand_in(&self) -> FxHashMap<SmolStr, Placeholder> {
let mut res = FxHashMap::default();
for t in &self.tokens {
if let PatternElement::Placeholder(placeholder) = t {
res.insert(SmolStr::new(placeholder.stand_in_name.clone()), placeholder.clone());
}
}
res
}
}
impl FromStr for SsrPattern {
type Err = SsrError;
fn from_str(pattern_str: &str) -> Result<SsrPattern, SsrError> {
let raw: RawSearchPattern = pattern_str.parse()?;
let raw_str = raw.as_rust_code();
let res = SsrPattern {
expr: ast::Expr::parse(&raw_str).ok().map(|n| n.syntax().clone()),
type_ref: ast::TypeRef::parse(&raw_str).ok().map(|n| n.syntax().clone()),
item: ast::ModuleItem::parse(&raw_str).ok().map(|n| n.syntax().clone()),
path: ast::Path::parse(&raw_str).ok().map(|n| n.syntax().clone()),
pattern: ast::Pat::parse(&raw_str).ok().map(|n| n.syntax().clone()),
placeholders_by_stand_in: raw.placeholders_by_stand_in(),
raw,
};
if res.expr.is_none()
&& res.type_ref.is_none()
&& res.item.is_none()
&& res.path.is_none()
&& res.pattern.is_none()
{
bail!("Pattern is not a valid Rust expression, type, item, path or pattern");
}
Ok(res)
}
}
impl FromStr for SsrTemplate {
type Err = SsrError;
fn from_str(pattern_str: &str) -> Result<SsrTemplate, SsrError> {
let tokens = parse_pattern(pattern_str)?;
// Validate that the template is a valid fragment of Rust code. We reuse the validation
// logic for search patterns since the only thing that differs is the error message.
if SsrPattern::from_str(pattern_str).is_err() {
bail!("Replacement is not a valid Rust expression, type, item, path or pattern");
}
// Our actual template needs to preserve whitespace, so we can't reuse `tokens`.
Ok(SsrTemplate { tokens })
}
}
/// Returns `pattern_str`, parsed as a search or replace pattern. If `remove_whitespace` is true,
/// then any whitespace tokens will be removed, which we do for the search pattern, but not for the
/// replace pattern.
fn parse_pattern(pattern_str: &str) -> Result<Vec<PatternElement>, SsrError> {
let mut res = Vec::new();
let mut placeholder_names = FxHashSet::default();
let mut tokens = tokenize(pattern_str)?.into_iter();
while let Some(token) = tokens.next() {
if token.kind == T![$] {
let placeholder = parse_placeholder(&mut tokens)?;
if !placeholder_names.insert(placeholder.ident.clone()) {
bail!("Name `{}` repeats more than once", placeholder.ident);
}
res.push(PatternElement::Placeholder(placeholder));
} else {
res.push(PatternElement::Token(token));
}
}
Ok(res)
}
/// Checks for errors in a rule. e.g. the replace pattern referencing placeholders that the search
/// pattern didn't define.
fn validate_rule(rule: &SsrRule) -> Result<(), SsrError> {
let mut defined_placeholders = FxHashSet::default();
for p in &rule.pattern.raw.tokens {
if let PatternElement::Placeholder(placeholder) = p {
defined_placeholders.insert(&placeholder.ident);
}
}
let mut undefined = Vec::new();
for p in &rule.template.tokens {
if let PatternElement::Placeholder(placeholder) = p {
if !defined_placeholders.contains(&placeholder.ident) {
undefined.push(format!("${}", placeholder.ident));
}
if !placeholder.constraints.is_empty() {
bail!("Replacement placeholders cannot have constraints");
}
}
}
if !undefined.is_empty() {
bail!("Replacement contains undefined placeholders: {}", undefined.join(", "));
}
Ok(())
}
fn tokenize(source: &str) -> Result<Vec<Token>, SsrError> {
let mut start = 0;
let (raw_tokens, errors) = ra_syntax::tokenize(source);
if let Some(first_error) = errors.first() {
bail!("Failed to parse pattern: {}", first_error);
}
let mut tokens: Vec<Token> = Vec::new();
for raw_token in raw_tokens {
let token_len = usize::from(raw_token.len);
tokens.push(Token {
kind: raw_token.kind,
text: SmolStr::new(&source[start..start + token_len]),
});
start += token_len;
}
Ok(tokens)
}
fn parse_placeholder(tokens: &mut std::vec::IntoIter<Token>) -> Result<Placeholder, SsrError> {
let mut name = None;
let mut constraints = Vec::new();
if let Some(token) = tokens.next() {
match token.kind {
SyntaxKind::IDENT => {
name = Some(token.text);
}
T!['{'] => {
let token =
tokens.next().ok_or_else(|| SsrError::new("Unexpected end of placeholder"))?;
if token.kind == SyntaxKind::IDENT {
name = Some(token.text);
}
loop {
let token = tokens
.next()
.ok_or_else(|| SsrError::new("Placeholder is missing closing brace '}'"))?;
match token.kind {
T![:] => {
constraints.push(parse_constraint(tokens)?);
}
T!['}'] => break,
_ => bail!("Unexpected token while parsing placeholder: '{}'", token.text),
}
}
}
_ => {
bail!("Placeholders should either be $name or ${{name:constraints}}");
}
}
}
let name = name.ok_or_else(|| SsrError::new("Placeholder ($) with no name"))?;
Ok(Placeholder::new(name, constraints))
}
fn parse_constraint(tokens: &mut std::vec::IntoIter<Token>) -> Result<Constraint, SsrError> {
let constraint_type = tokens
.next()
.ok_or_else(|| SsrError::new("Found end of placeholder while looking for a constraint"))?
.text
.to_string();
match constraint_type.as_str() {
"kind" => {
expect_token(tokens, "(")?;
let t = tokens.next().ok_or_else(|| {
SsrError::new("Unexpected end of constraint while looking for kind")
})?;
if t.kind != SyntaxKind::IDENT {
bail!("Expected ident, found {:?} while parsing kind constraint", t.kind);
}
expect_token(tokens, ")")?;
Ok(Constraint::Kind(NodeKind::from(&t.text)?))
}
"not" => {
expect_token(tokens, "(")?;
let sub = parse_constraint(tokens)?;
expect_token(tokens, ")")?;
Ok(Constraint::Not(Box::new(sub)))
}
x => bail!("Unsupported constraint type '{}'", x),
}
}
fn expect_token(tokens: &mut std::vec::IntoIter<Token>, expected: &str) -> Result<(), SsrError> {
if let Some(t) = tokens.next() {
if t.text == expected {
return Ok(());
}
bail!("Expected {} found {}", expected, t.text);
}
bail!("Expected {} found end of stream", expected);
}
impl NodeKind {
fn from(name: &SmolStr) -> Result<NodeKind, SsrError> {
Ok(match name.as_str() {
"literal" => NodeKind::Literal,
_ => bail!("Unknown node kind '{}'", name),
})
}
}
impl Placeholder {
fn new(name: SmolStr, constraints: Vec<Constraint>) -> Self {
Self { stand_in_name: format!("__placeholder_{}", name), constraints, ident: name }
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn parser_happy_case() {
fn token(kind: SyntaxKind, text: &str) -> PatternElement {
PatternElement::Token(Token { kind, text: SmolStr::new(text) })
}
fn placeholder(name: &str) -> PatternElement {
PatternElement::Placeholder(Placeholder::new(SmolStr::new(name), Vec::new()))
}
let result: SsrRule = "foo($a, $b) ==>> bar($b, $a)".parse().unwrap();
assert_eq!(
result.pattern.raw.tokens,
vec![
token(SyntaxKind::IDENT, "foo"),
token(T!['('], "("),
placeholder("a"),
token(T![,], ","),
token(SyntaxKind::WHITESPACE, " "),
placeholder("b"),
token(T![')'], ")"),
]
);
assert_eq!(
result.template.tokens,
vec![
token(SyntaxKind::IDENT, "bar"),
token(T!['('], "("),
placeholder("b"),
token(T![,], ","),
token(SyntaxKind::WHITESPACE, " "),
placeholder("a"),
token(T![')'], ")"),
]
);
}
}
|