Lower @ . to @ __dot__ not in parser but in Expr conversion (#146)

The reason to use `__dot__` is to allow `macro __dot__` to be defined in
normal Julia source. But doing this in the parser is an awkward special
case - better to do it later during some lowering step.  Here done in
Expr conversion.

Author: c42f

src/expr.jl

@@ -152,6 +152,9 @@ function _to_expr(node::SyntaxNode; iteration_spec=false, need_linenodes=true,
     loc = source_location(LineNumberNode, node.source, node.position)
     if headsym == :macrocall
         insert!(args, 2, loc)
+        if args[1] == Symbol("@.")
+            args[1] = Symbol("@__dot__")
+        end
     elseif headsym in (:call, :ref)
         # Julia's standard `Expr` ASTs have children stored in a canonical
         # order which is often not always source order. We permute the children

src/kinds.jl

@@ -852,7 +852,6 @@ const _kind_names =
         # like CORE_DOC_MACRO_NAME)
         "BEGIN_MACRO_NAMES"
             "MacroName"
-            "@."
             "StringMacroName"
             "CmdMacroName"
             "core_@doc"

src/parser.jl

@@ -2238,7 +2238,6 @@ function fix_macro_name_kind!(ps::ParseState, macro_name_position, name_kind=not
     end
     if isnothing(name_kind)
         name_kind = k == K"Identifier" ? K"MacroName" :
-                    k == K"."          ? K"@."        :
                     internal_error("unrecognized source kind for macro name ", k)
     end
     reset_node!(ps, macro_name_position, kind=name_kind)
@@ -2249,21 +2248,13 @@ end
 #
 # flisp: parse-macro-name
 function parse_macro_name(ps::ParseState)
+    # @! x   ==>  (macrocall @! x)
+    # @.. x  ==>  (macrocall @.. x)
+    # @$ x   ==>  (macrocall @$ x)
+    # @var"#" x   ==>  (macrocall (var #) @$ x)
     bump_disallowed_space(ps)
-    mark = position(ps)
-    k = peek(ps)
-    if k == K"."
-        # TODO: deal with __dot__ lowering in Expr conversion?
-        # @. y  ==>  (macrocall @__dot__ y)
-        bump(ps)
-    else
-        # @! x   ==>  (macrocall @! x)
-        # @.. x  ==>  (macrocall @.. x)
-        # @$ x   ==>  (macrocall @$ x)
-        # @var"#" x   ==>  (macrocall (var #) @$ x)
-        let ps = with_space_sensitive(ps)
-            parse_atom(ps, false)
-        end
+    let ps = with_space_sensitive(ps)
+        parse_atom(ps, false)
     end
 end
 
@@ -3402,7 +3393,6 @@ function parse_atom(ps::ParseState, check_identifiers=true)
     elseif leading_kind == K"@" # macro call
         # Macro names can be keywords
         # @end x  ==> (macrocall @end x)
-        # @. x y  ==> (macrocall @__dot__ x y)
         bump(ps, TRIVIA_FLAG)
         parse_macro_name(ps)
         parse_call_chain(ps, mark, true)

src/syntax_tree.jl

@@ -74,8 +74,6 @@ function SyntaxNode(source::SourceFile, raw::GreenNode{SyntaxHead}, position::In
             nothing
         elseif k == K"error"
             ErrorVal()
-        elseif k == K"@."
-            :var"@__dot__"
         elseif k == K"MacroName"
             Symbol("@$(normalize_identifier(val_str))")
         elseif k == K"StringMacroName"

test/parser.jl

@@ -315,7 +315,6 @@ tests = [
         "A.B.@x"    =>  "(macrocall (. (. A (quote B)) (quote @x)))"
         "@A.B.x"    =>  "(macrocall (. (. A (quote B)) (quote @x)))"
         "[email protected]"    =>  "(macrocall (. (. A (quote B)) (error-t) (quote @x)))"
-        "@. y"      =>  "(macrocall @__dot__ y)"
         "f.(a,b)"   =>  "(. f (tuple a b))"
         "f.(a=1; b=2)" => "(. f (tuple (= a 1) (parameters (= b 2))))" =>
             Expr(:., :f, Expr(:tuple, Expr(:parameters, Expr(:kw, :b, 2)), Expr(:kw, :a, 1)))
@@ -710,7 +709,7 @@ tests = [
         # Macro names can be keywords
         "@end x" => "(macrocall @end x)"
         # __dot__ macro
-        "@. x y" => "(macrocall @__dot__ x y)"
+        "@. x" => "(macrocall @. x)" => Expr(:macrocall, Symbol("@__dot__"), LineNumberNode(1), :x)
         # cmd strings
         "``"         =>  "(macrocall :(Core.var\"@cmd\") (cmdstring-r \"\"))"
         "`cmd`"      =>  "(macrocall :(Core.var\"@cmd\") (cmdstring-r \"cmd\"))"