Several refactoring and bugfix.

src/integration_tests/function_expansion_test.py

@@ -3,118 +3,124 @@
 from integration_tests import utils
 
 
-def test_expand_atan2_function() -> None:
+def test_atan2() -> None:
     def solve(x, y):
         return math.atan2(y, x)
 
-    latex = r"\mathrm{solve}(x, y) = \arctan{\left({\frac{y}{x}}\right)}"
+    latex = (
+        r"\mathrm{solve}(x, y) ="
+        r" \arctan \mathopen{}\left( \frac{y}{x} \mathclose{}\right)"
+    )
     utils.check_function(solve, latex, expand_functions={"atan2"})
 
 
-def test_expand_atan2_nested_function() -> None:
+def test_atan2_nested() -> None:
     def solve(x, y):
         return math.atan2(math.exp(y), math.exp(x))
 
-    latex = r"\mathrm{solve}(x, y) = \arctan{\left({\frac{e^{y}}{e^{x}}}\right)}"
+    latex = (
+        r"\mathrm{solve}(x, y) ="
+        r" \arctan \mathopen{}\left( \frac{e^{y}}{e^{x}} \mathclose{}\right)"
+    )
     utils.check_function(solve, latex, expand_functions={"atan2", "exp"})
 
 
-def test_expand_exp_function() -> None:
+def test_exp() -> None:
     def solve(x):
         return math.exp(x)
 
     latex = r"\mathrm{solve}(x) = e^{x}"
     utils.check_function(solve, latex, expand_functions={"exp"})
 
 
-def test_expand_exp_nested_function() -> None:
+def test_exp_nested() -> None:
     def solve(x):
         return math.exp(math.exp(x))
 
     latex = r"\mathrm{solve}(x) = e^{e^{x}}"
     utils.check_function(solve, latex, expand_functions={"exp"})
 
 
-def test_expand_exp2_function() -> None:
+def test_exp2() -> None:
     def solve(x):
         return math.exp2(x)
 
     latex = r"\mathrm{solve}(x) = {2}^{x}"
     utils.check_function(solve, latex, expand_functions={"exp2"})
 
 
-def test_expand_exp2_nested_function() -> None:
+def test_exp2_nested() -> None:
     def solve(x):
         return math.exp2(math.exp2(x))
 
     latex = r"\mathrm{solve}(x) = {2}^{{2}^{x}}"
     utils.check_function(solve, latex, expand_functions={"exp2"})
 
 
-def test_expand_expm1_function() -> None:
+def test_expm1() -> None:
     def solve(x):
         return math.expm1(x)
 
-    latex = r"\mathrm{solve}(x) = \exp{\left({x}\right)} - {1}"
+    latex = r"\mathrm{solve}(x) = \exp x - {1}"
     utils.check_function(solve, latex, expand_functions={"expm1"})
 
 
-def test_expand_expm1_nested_function() -> None:
+def test_expm1_nested() -> None:
     def solve(x, y, z):
         return math.expm1(math.pow(y, z))
 
     latex = r"\mathrm{solve}(x, y, z) = e^{y^{z}} - {1}"
     utils.check_function(solve, latex, expand_functions={"expm1", "exp", "pow"})
 
 
-def test_expand_hypot_function_without_attribute_access() -> None:
+def test_hypot_without_attribute() -> None:
     from math import hypot
 
     def solve(x, y, z):
         return hypot(x, y, z)
 
-    latex = r"\mathrm{solve}(x, y, z) = \sqrt{x^{{2}} + y^{{2}} + z^{{2}}}"
+    latex = r"\mathrm{solve}(x, y, z) = \sqrt{ x^{{2}} + y^{{2}} + z^{{2}} }"
     utils.check_function(solve, latex, expand_functions={"hypot"})
 
 
-def test_expand_hypot_function() -> None:
+def test_hypot() -> None:
     def solve(x, y, z):
         return math.hypot(x, y, z)
 
-    latex = r"\mathrm{solve}(x, y, z) = \sqrt{x^{{2}} + y^{{2}} + z^{{2}}}"
+    latex = r"\mathrm{solve}(x, y, z) = \sqrt{ x^{{2}} + y^{{2}} + z^{{2}} }"
     utils.check_function(solve, latex, expand_functions={"hypot"})
 
 
-def test_expand_hypot_nested_function() -> None:
+def test_hypot_nested() -> None:
     def solve(a, b, x, y):
         return math.hypot(math.hypot(a, b), x, y)
 
     latex = (
-        r"\mathrm{solve}(a, b, x, y) = "
-        r"\sqrt{"
-        r"\sqrt{a^{{2}} + b^{{2}}}^{{2}} + "
-        r"x^{{2}} + y^{{2}}}"
+        r"\mathrm{solve}(a, b, x, y) ="
+        r" \sqrt{ \sqrt{ a^{{2}} + b^{{2}} }^{{2}} + x^{{2}} + y^{{2}} }"
     )
     utils.check_function(solve, latex, expand_functions={"hypot"})
 
 
-def test_expand_log1p_function() -> None:
+def test_log1p() -> None:
     def solve(x):
         return math.log1p(x)
 
-    latex = r"\mathrm{solve}(x) = \log{\left({{1} + x}\right)}"
+    latex = r"\mathrm{solve}(x) = \log \mathopen{}\left( {1} + x \mathclose{}\right)"
     utils.check_function(solve, latex, expand_functions={"log1p"})
 
 
-def test_expand_log1p_nested_function() -> None:
+def test_log1p_nested() -> None:
     def solve(x):
         return math.log1p(math.exp(x))
 
-    latex = r"\mathrm{solve}(x) = \log{\left({{1} + e^{x}}\right)}"
+    latex = (
+        r"\mathrm{solve}(x) = \log \mathopen{}\left( {1} + e^{x} \mathclose{}\right)"
+    )
     utils.check_function(solve, latex, expand_functions={"log1p", "exp"})
 
 
-def test_expand_pow_nested_function() -> None:
+def test_pow_nested() -> None:
     def solve(w, x, y, z):
         return math.pow(math.pow(w, x), math.pow(y, z))
 
@@ -125,7 +131,7 @@ def solve(w, x, y, z):
     utils.check_function(solve, latex, expand_functions={"pow"})
 
 
-def test_expand_pow_function() -> None:
+def test_pow() -> None:
     def solve(x, y):
         return math.pow(x, y)
 

src/integration_tests/regression_test.py

@@ -11,7 +11,7 @@ def test_quadratic_solution() -> None:
     def solve(a, b, c):
         return (-b + math.sqrt(b**2 - 4 * a * c)) / (2 * a)
 
-    latex = r"\mathrm{solve}(a, b, c) = \frac{-b + \sqrt{b^{{2}} - {4} a c}}{{2} a}"
+    latex = r"\mathrm{solve}(a, b, c) = \frac{-b + \sqrt{ b^{{2}} - {4} a c }}{{2} a}"
     utils.check_function(solve, latex)
 
 
@@ -26,7 +26,7 @@ def sinc(x):
         r"\mathrm{sinc}(x) = "
         r"\left\{ \begin{array}{ll} "
         r"{1}, & \mathrm{if} \ "
-        r"{x = {0}} \\ \frac{\sin{\left({x}\right)}}{x}, & \mathrm{otherwise} "
+        r"{x = {0}} \\ \frac{\sin x}{x}, & \mathrm{otherwise} "
         r"\end{array} \right."
     )
     utils.check_function(sinc, latex)
@@ -201,9 +201,9 @@ def sigmoid(x):
         sigmoid,
         (
             r"\mathrm{sigmoid}(x) = \left\{ \begin{array}{ll} "
-            r"\frac{{1}}{{1} + \exp{\left({-x}\right)}}, & "
+            r"\frac{{1}}{{1} + \exp \mathopen{}\left( -x \mathclose{}\right)}, & "
             r"\mathrm{if} \ {x > {0}} \\ "
-            r"\frac{\exp{\left({x}\right)}}{\exp{\left({x}\right)} + {1}}, & "
+            r"\frac{\exp x}{\exp x + {1}}, & "
             r"\mathrm{otherwise} "
             r"\end{array} \right."
         ),

src/latexify/ast_utils.py

@@ -31,7 +31,7 @@ def make_name(id: str) -> ast.Name:
     return ast.Name(id=id, ctx=ast.Load())
 
 
-def make_attribute(value: ast.Expr, attr: str):
+def make_attribute(value: ast.expr, attr: str):
     """Generates a new Attribute node.
 
     Args:

src/latexify/codegen/function_codegen.py

@@ -52,6 +52,14 @@
     ast.Or: 10,
 }
 
+# NOTE(odashi):
+# Function invocation is treated as a unary operator with a higher precedence.
+# This ensures that the argument with a unary operator is wrapped:
+#     exp(x) --> \exp x
+#     exp(-x) --> \exp (-x)
+#     -exp(x) --> - \exp x
+_CALL_PRECEDENCE = _PRECEDENCES[ast.UAdd] + 1
+
 
 def _get_precedence(node: ast.AST) -> int:
     """Obtains the precedence of the subtree.
@@ -63,6 +71,9 @@ def _get_precedence(node: ast.AST) -> int:
         If `node` is a subtree with some operator, returns the precedence of the
         operator. Otherwise, returns a number larger enough from other precedences.
     """
+    if isinstance(node, ast.Call):
+        return _CALL_PRECEDENCE
+
     if isinstance(node, (ast.BoolOp, ast.BinOp, ast.UnaryOp)):
         return _PRECEDENCES[type(node.op)]
 
@@ -289,38 +300,34 @@ def visit_Return(self, node: ast.Return) -> str:
 
     def visit_Tuple(self, node: ast.Tuple) -> str:
         elts = [self.visit(i) for i in node.elts]
-        return (
-            r"\mathopen{}\left( "
-            + r"\space,\space ".join(elts)
-            + r"\mathclose{}\right) "
-        )
+        return r"\mathopen{}\left( " + r", ".join(elts) + r" \mathclose{}\right)"
 
     def visit_List(self, node: ast.List) -> str:
         elts = [self.visit(i) for i in node.elts]
-        return r"\left[ " + r"\space,\space ".join(elts) + r"\right] "
+        return r"\mathopen{}\left[ " + r", ".join(elts) + r" \mathclose{}\right]"
 
     def visit_Set(self, node: ast.Set) -> str:
         elts = [self.visit(i) for i in node.elts]
-        return r"\left\{ " + r"\space,\space ".join(elts) + r"\right\} "
+        return r"\mathopen{}\left\{ " + r", ".join(elts) + r" \mathclose{}\right\}"
 
     def visit_ListComp(self, node: ast.ListComp) -> str:
         generators = [self.visit(comp) for comp in node.generators]
         return (
-            r"\left[ "
+            r"\mathopen{}\left[ "
             + self.visit(node.elt)
             + r" \mid "
             + ", ".join(generators)
-            + r" \right]"
+            + r" \mathclose{}\right]"
         )
 
     def visit_SetComp(self, node: ast.SetComp) -> str:
         generators = [self.visit(comp) for comp in node.generators]
         return (
-            r"\left\{ "
+            r"\mathopen{}\left\{ "
             + self.visit(node.elt)
             + r" \mid "
             + ", ".join(generators)
-            + r" \right\}"
+            + r" \mathclose{}\right\}"
         )
 
     def visit_comprehension(self, node: ast.comprehension) -> str:
@@ -347,10 +354,16 @@ def _generate_sum_prod(self, node: ast.Call) -> str | None:
             return None
 
         name = ast_utils.extract_function_name_or_none(node)
-        assert name is not None
+        assert name in ("fsum", "sum", "prod")
+
+        command = {
+            "fsum": r"\sum",
+            "sum": r"\sum",
+            "prod": r"\prod",
+        }[name]
 
         elt, scripts = self._get_sum_prod_info(node.args[0])
-        scripts_str = [rf"\{name}_{{{lo}}}^{{{up}}}" for lo, up in scripts]
+        scripts_str = [rf"{command}_{{{lo}}}^{{{up}}}" for lo, up in scripts]
         return (
             " ".join(scripts_str)
             + rf" \mathopen{{}}\left({{{elt}}}\mathclose{{}}\right)"
@@ -403,7 +416,7 @@ def visit_Call(self, node: ast.Call) -> str:
         func_name = ast_utils.extract_function_name_or_none(node)
 
         # Special treatments for some functions.
-        if func_name in ("sum", "prod"):
+        if func_name in ("fsum", "sum", "prod"):
             special_latex = self._generate_sum_prod(node)
         elif func_name in ("array", "ndarray"):
             special_latex = self._generate_matrix(node)
@@ -413,17 +426,38 @@ def visit_Call(self, node: ast.Call) -> str:
         if special_latex is not None:
             return special_latex
 
-        # Function signature (possibly an expression).
-        default_func_str = self.visit(node.func)
-
-        # Obtains wrapper syntax: sqrt -> "\sqrt{" and "}"
-        lstr, rstr = constants.BUILTIN_FUNCS.get(
-            func_name,
-            (default_func_str + r"\mathopen{}\left(", r"\mathclose{}\right)"),
-        )
+        # Obtains the codegen rule.
+        rule = constants.BUILTIN_FUNCS.get(func_name)
+        if rule is None:
+            rule = constants.FunctionRule(self.visit(node.func))
+
+        if rule.is_unary and len(node.args) == 1:
+            # Unary function. Applies the same wrapping policy with the unary operators.
+            # NOTE(odashi):
+            # Factorial "x!" is treated as a special case: it requires both inner/outer
+            # parentheses for correct interpretation.
+            precedence = _get_precedence(node)
+            arg = node.args[0]
+            force_wrap = isinstance(arg, ast.Call) and (
+                func_name == "factorial"
+                or ast_utils.extract_function_name_or_none(arg) == "factorial"
+            )
+            arg_latex = self._wrap_operand(arg, precedence, force_wrap)
+            elements = [rule.left, arg_latex, rule.right]
+        else:
+            arg_latex = ", ".join(self.visit(arg) for arg in node.args)
+            if rule.is_wrapped:
+                elements = [rule.left, arg_latex, rule.right]
+            else:
+                elements = [
+                    rule.left,
+                    r"\mathopen{}\left(",
+                    arg_latex,
+                    r"\mathclose{}\right)",
+                    rule.right,
+                ]
 
-        arg_strs = [self.visit(arg) for arg in node.args]
-        return lstr + ", ".join(arg_strs) + rstr
+        return " ".join(x for x in elements if x)
 
     def visit_Attribute(self, node: ast.Attribute) -> str:
         vstr = self.visit(node.value)
@@ -481,20 +515,26 @@ def visit_NameConstant(self, node: ast.NameConstant) -> str:
     def visit_Ellipsis(self, node: ast.Ellipsis) -> str:
         return self._convert_constant(...)
 
-    def _wrap_operand(self, child: ast.expr, parent_prec: int) -> str:
+    def _wrap_operand(
+        self, child: ast.expr, parent_prec: int, force_wrap: bool = False
+    ) -> str:
         """Wraps the operand subtree with parentheses.
 
         Args:
             child: Operand subtree.
             parent_prec: Precedence of the parent operator.
+            force_wrap: Whether to wrap the operand or not when the precedence is equal.
 
         Returns:
             LaTeX form of `child`, with or without surrounding parentheses.
         """
         latex = self.visit(child)
-        if _get_precedence(child) >= parent_prec:
-            return latex
-        return rf"\mathopen{{}}\left( {latex} \mathclose{{}}\right)"
+        child_prec = _get_precedence(child)
+
+        if child_prec < parent_prec or force_wrap and child_prec == parent_prec:
+            return rf"\mathopen{{}}\left( {latex} \mathclose{{}}\right)"
+
+        return latex
 
     def _wrap_binop_operand(
         self,
@@ -515,6 +555,13 @@ def _wrap_binop_operand(
         if not operand_rule.wrap:
             return self.visit(child)
 
+        if isinstance(child, ast.Call):
+            rule = constants.BUILTIN_FUNCS.get(
+                ast_utils.extract_function_name_or_none(child)
+            )
+            if rule is not None and rule.is_wrapped:
+                return self.visit(child)
+
         if not isinstance(child, ast.BinOp):
             return self._wrap_operand(child, parent_prec)