regorus/src/builtins/sets.rs

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

use crate::ast::Expr;
use crate::builtins;
use crate::builtins::utils::{ensure_args_count, ensure_set};
use crate::lexer::Span;
use crate::value::Value;

use std::collections::{BTreeSet, HashMap};

use anyhow::{bail, Result};

pub fn register(m: &mut HashMap<&'static str, builtins::BuiltinFcn>) {
    m.insert("intersection", intersection_of_set_of_sets);
    m.insert("union", union_of_set_of_sets);
}

pub fn intersection(expr1: &Expr, expr2: &Expr, v1: Value, v2: Value) -> Result<Value> {
    let s1 = ensure_set("intersection", expr1, v1)?;
    let s2 = ensure_set("intersection", expr2, v2)?;
    Ok(Value::from_set(s1.intersection(&s2).cloned().collect()))
}

pub fn union(expr1: &Expr, expr2: &Expr, v1: Value, v2: Value) -> Result<Value> {
    let s1 = ensure_set("union", expr1, v1)?;
    let s2 = ensure_set("union", expr2, v2)?;
    Ok(Value::from_set(s1.union(&s2).cloned().collect()))
}

pub fn difference(expr1: &Expr, expr2: &Expr, v1: Value, v2: Value) -> Result<Value> {
    let s1 = ensure_set("difference", expr1, v1)?;
    let s2 = ensure_set("difference", expr2, v2)?;
    Ok(Value::from_set(s1.difference(&s2).cloned().collect()))
}

fn intersection_of_set_of_sets(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
    let name = "intersection";
    ensure_args_count(span, name, params, args, 1)?;
    let set = ensure_set(name, &params[0], args[0].clone())?;

    let mut res = BTreeSet::new();
    let mut first = true;

    for s in set.iter() {
        let s = match s {
            Value::Set(s) => s,
            _ => bail!(
                span.error(format!("`{name}` expects set of sets. Got `{}`", args[0]).as_str())
            ),
        };

        if first {
            res = (**s).clone();
            first = false;
        } else {
            res = res.intersection(s).cloned().collect();
        }
    }

    Ok(Value::from_set(res))
}

fn union_of_set_of_sets(span: &Span, params: &[Expr], args: &[Value]) -> Result<Value> {
    let name = "union";
    ensure_args_count(span, name, params, args, 1)?;
    let set = ensure_set(name, &params[0], args[0].clone())?;

    let mut res = BTreeSet::new();

    for s in set.iter() {
        let s = match s {
            Value::Set(s) => s,
            _ => bail!(
                span.error(format!("`{name}` expects set of sets. Got `{}`", args[0]).as_str())
            ),
        };

        res = res.union(s).cloned().collect();
    }

    Ok(Value::from_set(res))
}