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Functions
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use crate::errors::RecoverableParseError;
use crate::parser::traversal::WalkDFS;
use capitalize::Capitalize;
use std::collections::HashSet;
use tree_sitter::Node;
pub fn detect_syntactic_errors(
source: &str,
tree: &tree_sitter::Tree,
errors: &mut Vec<RecoverableParseError>,
) {
let mut malformed_lines_reported = HashSet::new();
let root_node = tree.root_node();
let retract: &dyn Fn(&tree_sitter::Node) -> bool = &|node: &tree_sitter::Node| {
node.is_missing() || node.is_error() || node.start_position() == node.end_position()
};
for node in WalkDFS::with_retract(&root_node, &retract) {
if node.start_position() == node.end_position() {
errors.push(classify_missing_token(node));
continue;
}
if node.is_error() {
let line = node.start_position().row;
// If this line has already been reported as malformed, skip all error nodes on this line
if malformed_lines_reported.contains(&line) {
if is_malformed_line_error(&node, source) {
malformed_lines_reported.insert(line);
let start_byte = node.start_byte();
let end_byte = node.end_byte();
let last_char = source.lines().nth(line).map_or(0, |l| l.len());
errors.push(RecoverableParseError::new(
format!(
"Malformed line {}: '{}'",
line + 1,
source.lines().nth(line).unwrap_or("")
),
Some(tree_sitter::Range {
start_byte,
end_byte,
start_point: tree_sitter::Point {
row: line,
column: 0,
},
end_point: tree_sitter::Point {
column: last_char,
}),
));
} else {
errors.push(classify_unexpected_token_error(node, source));
/// Classifies a missing token node and generates a diagnostic with a context-aware message.
fn classify_missing_token(node: Node) -> RecoverableParseError {
let start = node.start_position();
let end = node.end_position();
let message = if let Some(parent) = node.parent() {
match parent.kind() {
"letting_statement" => "Missing Expression or Domain".to_string(),
_ => format!("Missing {}", user_friendly_token_name(node.kind(), false)),
format!("Missing {}", user_friendly_token_name(node.kind(), false))
RecoverableParseError::new(
message,
start_byte: node.start_byte(),
end_byte: node.end_byte(),
start_point: start,
end_point: end,
)
/// Classifies an unexpected token error node and generates a diagnostic.
fn classify_unexpected_token_error(node: Node, source_code: &str) -> RecoverableParseError {
let start_byte = node.start_byte().min(source_code.len());
let end_byte = node.end_byte().min(source_code.len());
let src_token = &source_code[start_byte..end_byte];
if parent.kind() == "program"
// ERROR node is the direct child of the root node
{
// A case where the unexpected token is at the end of a valid statement
format!("Unexpected {}", src_token)
// }
// Unexpected token inside a construct
"Unexpected {} inside {}",
src_token,
user_friendly_token_name(parent.kind(), true)
// Should never happen since an ERROR node would always have a parent.
"Unexpected token".to_string()
start_point: node.start_position(),
end_point: node.end_position(),
/// Determines if an error node represents a malformed line error.
fn is_malformed_line_error(node: &tree_sitter::Node, source: &str) -> bool {
if node.start_position().column == 0 || error_node_out_of_range(node, source) {
return true;
let parent = node.parent();
let grandparent = parent.and_then(|n| n.parent());
let root = grandparent.and_then(|n| n.parent());
if let (Some(parent), Some(grandparent), Some(root)) = (parent, grandparent, root) {
parent.kind() == "set_operation_bool"
&& grandparent.kind() == "bool_expr"
&& root.kind() == "program"
false
/// Coverts a token name into a more user-friendly format for error messages.
/// Removes underscores, replaces certain keywords with more natural language, and adds appropriate articles.
fn user_friendly_token_name(token: &str, article: bool) -> String {
let capitalized = if token.contains("atom") {
"Expression".to_string()
} else if token == "COLON" {
":".to_string()
let friendly_name = token
.replace("literal", "")
.replace("int", "Integer")
.replace("expr", "Expression")
.replace('_', " ");
friendly_name
.split_whitespace()
.map(|word| word.capitalize())
.collect::<Vec<_>>()
.join(" ")
if !article {
return capitalized;
let first_char = capitalized.chars().next().unwrap();
let article = match first_char.to_ascii_lowercase() {
'a' | 'e' | 'i' | 'o' | 'u' => "an",
_ => "a",
format!("{} {}", article, capitalized)
/// Returns true if the node's start or end column is out of range for its line in the source.
fn error_node_out_of_range(node: &tree_sitter::Node, source: &str) -> bool {
let lines: Vec<&str> = source.lines().collect();
let start_line_len = lines.get(start.row).map_or(0, |l| l.len());
let end_line_len = lines.get(end.row).map_or(0, |l| l.len());
(start.column > start_line_len) || (end.column > end_line_len)
#[cfg(test)]
mod test {
use super::{detect_syntactic_errors, is_malformed_line_error, user_friendly_token_name};
use crate::{parser::traversal::WalkDFS, util::get_tree};
/// Helper function for tests to compare the actual error with the expected one.
fn assert_essence_parse_error_eq(a: &RecoverableParseError, b: &RecoverableParseError) {
assert_eq!(a.msg, b.msg, "error messages differ");
assert_eq!(a.range, b.range, "error ranges differ");
#[test]
fn malformed_line() {
let source = " a,a,b: int(1..3)";
let (tree, _) = get_tree(source).expect("Should parse");
let error_node = WalkDFS::with_retract(&root_node, &|_node| false)
.find(|node| node.is_error())
.expect("Should find an error node");
assert!(is_malformed_line_error(&error_node, source));
fn user_friendly_token_name_article() {
assert_eq!(
user_friendly_token_name("int_domain", false),
"Integer Domain"
);
user_friendly_token_name("int_domain", true),
"an Integer Domain"
// assert_eq!(user_friendly_token_name("atom", true), "an Expression");
assert_eq!(user_friendly_token_name("COLON", false), ":");
fn missing_domain() {
let source = "find x:";
let mut errors = vec![];
detect_syntactic_errors(source, &tree, &mut errors);
assert_eq!(errors.len(), 1, "Expected exactly one diagnostic");
let error = &errors[0];
assert_essence_parse_error_eq(
error,
&RecoverableParseError::new(
"Missing Domain".to_string(),
start_byte: 7,
end_byte: 7,
start_point: tree_sitter::Point { row: 0, column: 7 },
end_point: tree_sitter::Point { row: 0, column: 7 },