bun.sh/src/ast/TS.zig

/// This is for TypeScript "enum" and "namespace" blocks. Each block can
/// potentially be instantiated multiple times. The exported members of each
/// block are merged into a single namespace while the non-exported code is
/// still scoped to just within that block:
///
///    let x = 1;
///    namespace Foo {
///      let x = 2;
///      export let y = 3;
///    }
///    namespace Foo {
///      console.log(x); // 1
///      console.log(y); // 3
///    }
///
/// Doing this also works inside an enum:
///
///    enum Foo {
///      A = 3,
///      B = A + 1,
///    }
///    enum Foo {
///      C = A + 2,
///    }
///    console.log(Foo.B) // 4
///    console.log(Foo.C) // 5
///
/// This is a form of identifier lookup that works differently than the
/// hierarchical scope-based identifier lookup in JavaScript. Lookup now needs
/// to search sibling scopes in addition to parent scopes. This is accomplished
/// by sharing the map of exported members between all matching sibling scopes.
pub const TSNamespaceScope = struct {
    /// This is specific to this namespace block. It's the argument of the
    /// immediately-invoked function expression that the namespace block is
    /// compiled into:
    ///
    ///   var ns;
    ///   (function (ns2) {
    ///     ns2.x = 123;
    ///   })(ns || (ns = {}));
    ///
    /// This variable is "ns2" in the above example. It's the symbol to use when
    /// generating property accesses off of this namespace when it's in scope.
    arg_ref: Ref,

    /// This is shared between all sibling namespace blocks
    exported_members: *TSNamespaceMemberMap,

    /// This is a lazily-generated map of identifiers that actually represent
    /// property accesses to this namespace's properties. For example:
    ///
    ///   namespace x {
    ///     export let y = 123
    ///   }
    ///   namespace x {
    ///     export let z = y
    ///   }
    ///
    /// This should be compiled into the following code:
    ///
    ///   var x;
    ///   (function(x2) {
    ///     x2.y = 123;
    ///   })(x || (x = {}));
    ///   (function(x3) {
    ///     x3.z = x3.y;
    ///   })(x || (x = {}));
    ///
    /// When we try to find the symbol "y", we instead return one of these lazily
    /// generated proxy symbols that represent the property access "x3.y". This
    /// map is unique per namespace block because "x3" is the argument symbol that
    /// is specific to that particular namespace block.
    property_accesses: bun.StringArrayHashMapUnmanaged(Ref) = .{},

    /// Even though enums are like namespaces and both enums and namespaces allow
    /// implicit references to properties of sibling scopes, they behave like
    /// separate, er, namespaces. Implicit references only work namespace-to-
    /// namespace and enum-to-enum. They do not work enum-to-namespace. And I'm
    /// not sure what's supposed to happen for the namespace-to-enum case because
    /// the compiler crashes: https://github.com/microsoft/TypeScript/issues/46891.
    /// So basically these both work:
    ///
    ///   enum a { b = 1 }
    ///   enum a { c = b }
    ///
    ///   namespace x { export let y = 1 }
    ///   namespace x { export let z = y }
    ///
    /// This doesn't work:
    ///
    ///   enum a { b = 1 }
    ///   namespace a { export let c = b }
    ///
    /// And this crashes the TypeScript compiler:
    ///
    ///   namespace a { export let b = 1 }
    ///   enum a { c = b }
    ///
    /// Therefore we only allow enum/enum and namespace/namespace interactions.
    is_enum_scope: bool,
};

pub const TSNamespaceMemberMap = bun.StringArrayHashMapUnmanaged(TSNamespaceMember);

pub const TSNamespaceMember = struct {
    loc: logger.Loc,
    data: Data,

    pub const Data = union(enum) {
        /// "namespace ns { export let it }"
        property,
        /// "namespace ns { export namespace it {} }"
        namespace: *TSNamespaceMemberMap,
        /// "enum ns { it }"
        enum_number: f64,
        /// "enum ns { it = 'it' }"
        enum_string: *E.String,
        /// "enum ns { it = something() }"
        enum_property: void,

        pub fn isEnum(data: Data) bool {
            return switch (data) {
                inline else => |_, tag| comptime std.mem.startsWith(u8, @tagName(tag), "enum_"),
            };
        }
    };
};

pub const Class = G.Class;

const std = @import("std");

const bun = @import("bun");
const logger = bun.logger;

const js_ast = bun.ast;
const E = js_ast.E;
const G = js_ast.G;
const Ref = js_ast.Ref;