mago-analyzer 1.18.1

A PHP static analyzer that can detect type errors in PHP code, and provide suggestions for fixing them.
Documentation 
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//! `json_encode()` return type provider.

use mago_codex::ttype::atomic::TAtomic;
use mago_codex::ttype::atomic::scalar::TScalar;
use mago_codex::ttype::atomic::scalar::bool::TBool;
use mago_codex::ttype::atomic::scalar::string::TString;
use mago_codex::ttype::get_non_empty_string;
use mago_codex::ttype::union::TUnion;
use mago_syntax::ast::Binary;
use mago_syntax::ast::BinaryOperator;
use mago_syntax::ast::Expression;

use crate::plugin::context::InvocationInfo;
use crate::plugin::context::ProviderContext;
use crate::plugin::provider::Provider;
use crate::plugin::provider::ProviderMeta;
use crate::plugin::provider::function::FunctionReturnTypeProvider;
use crate::plugin::provider::function::FunctionTarget;

const JSON_THROW_ON_ERROR: i64 = 4_194_304;

static META: ProviderMeta = ProviderMeta::new(
    "php::json::json_encode",
    "json_encode",
    "Returns non-empty-string when JSON_THROW_ON_ERROR is set, otherwise string|false",
);

/// Provider for the `json_encode()` function.
///
/// When `JSON_THROW_ON_ERROR` flag is set, returns `non-empty-string`.
/// Otherwise returns `non-empty-string|false`.
#[derive(Default)]
pub struct JsonEncodeProvider;

impl Provider for JsonEncodeProvider {
    fn meta() -> &'static ProviderMeta {
        &META
    }
}

impl FunctionReturnTypeProvider for JsonEncodeProvider {
    fn targets() -> FunctionTarget {
        FunctionTarget::Exact("json_encode")
    }

    fn get_return_type(
        &self,
        context: &ProviderContext<'_, '_, '_>,
        invocation: &InvocationInfo<'_, '_, '_>,
    ) -> Option<TUnion> {
        let flags_argument = invocation.get_argument(1, &["flags"])?;
        let flags_type = context.get_expression_type(flags_argument)?;

        let throws = match flags_type.get_single_literal_int_value() {
            Some(value) => value & JSON_THROW_ON_ERROR > 0,
            None => flags_contain_throw_on_error(context, flags_argument),
        };

        Some(if throws {
            get_non_empty_string()
        } else {
            TUnion::from_vec(vec![
                TAtomic::Scalar(TScalar::String(TString::non_empty())),
                TAtomic::Scalar(TScalar::Bool(TBool::r#false())),
            ])
        })
    }
}

fn flags_contain_throw_on_error(context: &ProviderContext<'_, '_, '_>, expr: &Expression<'_>) -> bool {
    match expr {
        Expression::Binary(Binary { lhs, operator: BinaryOperator::BitwiseOr(_), rhs }) => {
            flags_contain_throw_on_error(context, lhs) || flags_contain_throw_on_error(context, rhs)
        }
        Expression::Parenthesized(parenthesized) => flags_contain_throw_on_error(context, parenthesized.expression),
        _ => context
            .get_expression_type(expr)
            .and_then(|ty| ty.get_single_literal_int_value())
            .is_some_and(|value| value & JSON_THROW_ON_ERROR > 0),
    }
}