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use std::fs;
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use std::sync::{Arc, RwLock};
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use conjure_cp_core::Model;
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use conjure_cp_core::ast::{DeclarationPtr, Expression, Metadata, Moo};
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use conjure_cp_core::context::Context;
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#[allow(unused)]
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use uniplate::Uniplate;
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use super::find::parse_find_statement;
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use super::letting::parse_letting_statement;
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use super::util::{get_tree, named_children};
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use crate::errors::EssenceParseError;
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use crate::expression::parse_expression;
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/// Parse an Essence file into a Model using the tree-sitter parser.
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pub fn parse_essence_file_native(
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    path: &str,
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    context: Arc<RwLock<Context<'static>>>,
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) -> Result<Model, EssenceParseError> {
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    let source_code = fs::read_to_string(path)
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        .unwrap_or_else(|_| panic!("Failed to read the source code file {path}"));
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    parse_essence_with_context(&source_code, context)
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}
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pub fn parse_essence_with_context(
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    src: &str,
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    context: Arc<RwLock<Context<'static>>>,
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) -> Result<Model, EssenceParseError> {
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    let (tree, source_code) = match get_tree(src) {
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        Some(tree) => tree,
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        None => {
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            return Err(EssenceParseError::TreeSitterError(
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                "Failed to parse source code".to_string(),
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            ));
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        }
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    };
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    let mut model = Model::new(context);
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    // let symbols = model.as_submodel().symbols().clone();
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    let root_node = tree.root_node();
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    let symbols_ptr = model.as_submodel().symbols_ptr_unchecked().clone();
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    for statement in named_children(&root_node) {
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        match statement.kind() {
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            "single_line_comment" => {}
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            "language_declaration" => {}
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            "find_statement" => {
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                let var_hashmap =
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                    parse_find_statement(statement, &source_code, Some(symbols_ptr.clone()))?;
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                for (name, domain) in var_hashmap {
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                    model
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                        .as_submodel_mut()
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                        .symbols_mut()
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                        .insert(DeclarationPtr::new_var(name, domain));
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                }
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            }
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            "bool_expr" | "atom" | "comparison_expr" => {
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                model.as_submodel_mut().add_constraint(parse_expression(
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                    statement,
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                    &source_code,
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                    &statement,
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                    Some(symbols_ptr.clone()),
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                )?);
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            }
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            "language_label" => {}
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            "letting_statement" => {
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                let letting_vars =
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                    parse_letting_statement(statement, &source_code, Some(symbols_ptr.clone()))?;
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                model.as_submodel_mut().symbols_mut().extend(letting_vars);
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            }
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            "dominance_relation" => {
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                let inner = statement
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                    .child_by_field_name("expression")
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                    .expect("Expected a sub-expression inside `dominanceRelation`");
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                let expr =
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                    parse_expression(inner, &source_code, &statement, Some(symbols_ptr.clone()))?;
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                let dominance = Expression::DominanceRelation(Metadata::new(), Moo::new(expr));
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                if model.dominance.is_some() {
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                    return Err(EssenceParseError::syntax_error(
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                        "Duplicate dominance relation".to_string(),
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                        None,
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                    ));
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                }
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                model.dominance = Some(dominance);
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            }
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            "ERROR" => {
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                let raw_expr = &source_code[statement.start_byte()..statement.end_byte()];
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                return Err(EssenceParseError::syntax_error(
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                    format!("'{raw_expr}' is not a valid expression"),
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                    Some(statement.range()),
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                ));
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            }
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            _ => {
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                let kind = statement.kind();
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                return Err(EssenceParseError::syntax_error(
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                    format!("Unrecognized top level statement kind: {kind}"),
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                    Some(statement.range()),
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                ));
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            }
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        }
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        // check for errors (keyword as identifier)
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        let result = keyword_as_identifier(root_node, &source_code);
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        result?
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    }
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    Ok(model)
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}
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const KEYWORDS: [&str; 21] = [
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    "forall", "exists", "such", "that", "letting", "find", "minimise", "maximise", "subject", "to",
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    "where", "and", "or", "not", "if", "then", "else", "in", "sum", "product", "bool",
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];
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fn keyword_as_identifier(root: tree_sitter::Node, src: &str) -> Result<(), EssenceParseError> {
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    let mut stack = vec![root];
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    while let Some(node) = stack.pop() {
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        if (node.kind() == "variable" || node.kind() == "identifier" || node.kind() == "parameter")
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            && let Ok(text) = node.utf8_text(src.as_bytes())
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        {
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            let ident = text.trim();
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            if KEYWORDS.contains(&ident) {
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                let start_point = node.start_position();
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                let end_point = node.end_position();
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                return Err(EssenceParseError::syntax_error(
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                    format!("Keyword '{ident}' used as identifier"),
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                    Some(tree_sitter::Range {
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                        start_byte: node.start_byte(),
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                        end_byte: node.end_byte(),
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                        start_point,
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                        end_point,
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                    }),
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                ));
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            }
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        }
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        // push children onto stack
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        for i in 0..node.child_count() {
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            if let Some(child) = node.child(i) {
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                stack.push(child);
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            }
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        }
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    }
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    Ok(())
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}
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pub fn parse_essence(src: &str) -> Result<Model, EssenceParseError> {
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    let context = Arc::new(RwLock::new(Context::default()));
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    parse_essence_with_context(src, context)
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}
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mod test {
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    #[allow(unused_imports)]
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    use crate::parse_essence;
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    #[allow(unused_imports)]
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    use conjure_cp_core::ast::{Atom, Expression, Metadata, Moo, Name};
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    #[allow(unused_imports)]
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    use conjure_cp_core::{domain_int, matrix_expr, range};
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    #[allow(unused_imports)]
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    use std::ops::Deref;
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    #[test]
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    pub fn test_parse_xyz() {
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        let src = "
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        find x, y, z : int(1..4)
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        such that x + y + z = 4
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        such that x >= y
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        ";
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        let model = parse_essence(src).unwrap();
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        let st = model.as_submodel().symbols();
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        let x = st.lookup(&Name::user("x")).unwrap();
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        let y = st.lookup(&Name::user("y")).unwrap();
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        let z = st.lookup(&Name::user("z")).unwrap();
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        assert_eq!(x.domain(), Some(domain_int!(1..4)));
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        assert_eq!(y.domain(), Some(domain_int!(1..4)));
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        assert_eq!(z.domain(), Some(domain_int!(1..4)));
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        let constraints = model.as_submodel().constraints();
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        assert_eq!(constraints.len(), 2);
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        let c1 = constraints[0].clone();
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        let x_e = Expression::Atomic(Metadata::new(), Atom::new_ref(x));
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        let y_e = Expression::Atomic(Metadata::new(), Atom::new_ref(y));
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        let z_e = Expression::Atomic(Metadata::new(), Atom::new_ref(z));
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        assert_eq!(
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            c1,
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            Expression::Eq(
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                Metadata::new(),
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                Moo::new(Expression::Sum(
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                    Metadata::new(),
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                    Moo::new(matrix_expr!(
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                        Expression::Sum(
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                            Metadata::new(),
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                            Moo::new(matrix_expr!(x_e.clone(), y_e.clone()))
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                        ),
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                        z_e
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                    ))
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                )),
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                Moo::new(Expression::Atomic(Metadata::new(), 4.into()))
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            )
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        );
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        let c2 = constraints[1].clone();
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        assert_eq!(
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            c2,
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            Expression::Geq(Metadata::new(), Moo::new(x_e), Moo::new(y_e))
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        );
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    }
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    #[test]
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    pub fn test_parse_letting_index() {
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        let src = "
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        letting a be [ [ 1,2,3 ; int(1,2,4) ], [ 1,3,2 ; int(1,2,4) ], [ 3,2,1 ; int(1,2,4) ] ; int(-2..0) ]
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        find b: int(1..5)
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        such that
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        b < a[-2,2],
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        allDiff(a[-2,..])
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        ";
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        let model = parse_essence(src).unwrap();
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        let st = model.as_submodel().symbols();
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        let a_decl = st.lookup(&Name::user("a")).unwrap();
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        let a = a_decl.as_value_letting().unwrap().deref().clone();
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        assert_eq!(
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            a,
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            matrix_expr!(
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                matrix_expr!(1.into(), 2.into(), 3.into() ; domain_int!(1, 2, 4)),
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                matrix_expr!(1.into(), 3.into(), 2.into() ; domain_int!(1, 2, 4)),
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                matrix_expr!(3.into(), 2.into(), 1.into() ; domain_int!(1, 2, 4));
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                domain_int!(-2..0)
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            )
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        )
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    }
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}