OutputForm

mathics/builtin/forms/output.py

@@ -37,6 +37,7 @@
     StringLParen,
     StringRParen,
     eval_baseform,
+    eval_makeboxes_outputform,
     eval_mathmlform,
     eval_tableform,
     eval_texform,
@@ -490,8 +491,13 @@ class OutputForm(FormBaseClass):
      = -Graphics-
     """
 
+    formats = {"OutputForm[s_String]": "s"}
     summary_text = "plain-text output format"
 
+    def eval_makeboxes(self, expr, form, evaluation):
+        """MakeBoxes[OutputForm[expr_], form_]"""
+        return eval_makeboxes_outputform(expr, evaluation, form)
+
 
 class PythonForm(FormBaseClass):
     """

mathics/eval/makeboxes/__init__.py

@@ -8,6 +8,7 @@
     eval_generic_makeboxes,
     eval_makeboxes,
     eval_makeboxes_fullform,
+    eval_makeboxes_outputform,
     format_element,
     int_to_string_shorter_repr,
     to_boxes,
@@ -19,20 +20,26 @@
     eval_tableform,
     eval_texform,
 )
-from mathics.eval.makeboxes.precedence import builtins_precedence, parenthesize
+from mathics.eval.makeboxes.precedence import (
+    builtins_precedence,
+    compare_precedence,
+    parenthesize,
+)
 
 __all__ = [
     "NumberForm_to_String",
     "StringLParen",
     "StringRParen",
     "_boxed_string",
     "builtins_precedence",
+    "compare_precedence",
     "do_format",
     "eval_baseform",
     "eval_generic_makeboxes",
     "eval_infix",
     "eval_makeboxes",
     "eval_makeboxes_fullform",
+    "eval_makeboxes_outputform",
     "eval_mathmlform",
     "eval_postprefix",
     "eval_tableform",

mathics/eval/makeboxes/makeboxes.py

@@ -21,6 +21,7 @@
 )
 from mathics.core.systemsymbols import (  # SymbolRule, SymbolRuleDelayed,
     SymbolComplex,
+    SymbolOutputForm,
     SymbolRational,
     SymbolStandardForm,
 )
@@ -136,6 +137,19 @@ def int_to_string_shorter_repr(value: int, form: Symbol, max_digits=640):
     return String(value_str)
 
 
+def eval_makeboxes_outputform(expr, evaluation, form):
+    """
+    Build a 2D representation of the expression using only keyboard characters.
+    """
+    from mathics.builtin.box.layout import InterpretationBox, PaneBox
+    from mathics.format.outputform import expression_to_outputform_text
+
+    text_outputform = str(expression_to_outputform_text(expr, evaluation, form))
+    elem1 = PaneBox(String(text_outputform))
+    elem2 = Expression(SymbolOutputForm, expr)
+    return InterpretationBox(elem1, elem2)
+
+
 # TODO: evaluation is needed because `atom_to_boxes` uses it. Can we remove this
 # argument?
 def eval_makeboxes_fullform(
@@ -265,10 +279,29 @@ def format_element(
     """
     Applies formats associated to the expression, and then calls Makeboxes
     """
+    # Halt any potential evaluation tracing while performing boxing.
     evaluation.is_boxing = True
+    while element.get_head() is form:
+        element = element.elements[0]
+
+    if element.has_form("FullForm", 1):
+        return eval_makeboxes_fullform(element.elements[0], evaluation)
+
+    # In order to work like in WMA, `format_element`
+    # should evaluate `MakeBoxes[element//form, StandardForm]`
+    # Then, MakeBoxes[expr_, StandardForm], for any expr,
+    # should apply Format[...] rules, and then
+    # MakeBoxes[...] rules. These rules should be stored
+    # as FormatValues[...]
+    # As a first step in that direction, let's mimic this behaviour
+    # just for the case of OutputForm:
+    if element.has_form("OutputForm", 1):
+        return eval_makeboxes_outputform(element.elements[0], evaluation, form)
+
     formatted_expr = do_format(element, evaluation, form)
     if formatted_expr is None:
         return None
+
     result_box = eval_makeboxes(formatted_expr, evaluation, form)
     if isinstance(result_box, String):
         return result_box