Support %-based string formatting

aten/src/ATen/core/interned_strings.h

@@ -185,6 +185,7 @@ namespace c10 {
   _(aten, append)                    \
   _(aten, item)                      \
   _(aten, format)                    \
+  _(aten, percentFormat)             \
   _(aten, __not__)                   \
   _(aten, __is__)                    \
   _(aten, __isnot__)                 \

test/jit/test_string_formatting.py

@@ -0,0 +1,148 @@
+import os
+import sys
+
+import torch
+from typing import List
+
+# Make the helper files in test/ importable
+pytorch_test_dir = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+sys.path.append(pytorch_test_dir)
+from torch.testing._internal.jit_utils import JitTestCase
+
+if __name__ == '__main__':
+    raise RuntimeError("This test file is not meant to be run directly, use:\n\n"
+                       "\tpython test/test_jit.py TESTNAME\n\n"
+                       "instead.")
+
+class TestStringFormatting(JitTestCase):
+
+    def test_modulo_operator(self):
+        def fn(dividend: int, divisor: int) -> int:
+            return dividend % divisor
+        self.checkScript(fn, (5, 2))
+
+    def test_string_interpolation_with_string_placeholder_and_string_variable(self):
+        def fn(arg1: str):
+            return "%s in template" % arg1
+        self.checkScript(fn, ("foo",))
+
+    def test_string_interpolation_with_string_placeholder_and_format_string_variable(self):
+        def fn(arg1: str):
+            return arg1 % "foo"
+        self.checkScript(fn, ("%s in template",))
+
+    def test_string_interpolation_with_double_percent_in_string(self):
+        def fn(arg1: str):
+            return "%s in template %%" % arg1
+        self.checkScript(fn, ("foo",))
+
+    def test_string_interpolation_with_percent_in_string(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%s in template %" % arg1    # noqa: F501
+
+        with self.assertRaisesRegex(RuntimeError, "Incomplete format specifier"):
+            fn("foo")
+
+    def test_string_interpolation_with_string_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%s in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_digit_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%d in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_alternate_digit_placeholder(self):
+        def fn(arg1: int) -> str:
+            return "%i in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_digit_placeholder_and_string_variable(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%d in template" % arg1
+
+        with self.assertRaisesRegex(RuntimeError, "%d requires a number for formatting, but got String"):
+            fn("1")
+
+    def test_string_interpolation_with_exponent_placeholder_and_string_variable(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%e in template" % arg1
+
+        with self.assertRaisesRegex(RuntimeError, "%e requires a number for formatting, but got String"):
+            fn("1")
+
+    def test_string_interpolation_with_lowercase_exponent_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%e in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_capital_exponent_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%E in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_float_placeholder_and_float_variable(self):
+        def fn(arg1: float) -> str:
+            return "%f in template" % arg1
+        self.checkScript(fn, (1.0,))
+
+    def test_string_interpolation_with_float_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%f in template" % arg1
+        self.checkScript(fn, (1,))
+
+    def test_string_interpolation_with_char_placeholder_and_char_variable(self):
+        def fn(arg1: str) -> str:
+            return "%c in template" % arg1
+        self.checkScript(fn, ("a",))
+
+    def test_string_interpolation_with_char_placeholder_and_digit_variable(self):
+        def fn(arg1: int) -> str:
+            return "%c in template" % arg1
+        self.checkScript(fn, (97,))
+
+    def test_string_interpolation_with_char_placeholder_and_true_string_variable(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%c in template" % arg1
+
+        with self.assertRaisesRegex(RuntimeError, "%c requires an int or char for formatting, but got String"):
+            fn("foo")
+
+    def test_string_interpolation_with_multiple_placeholders(self):
+        def fn(arg1: str, arg2: int, arg3: float) -> str:
+            return "%s %d %f in template" % (arg1, arg2, arg3)
+        self.checkScript(fn, ("foo", 1, 1))
+
+    def test_string_interpolation_with_subscript(self):
+        def fn(arg1: List[str]) -> str:
+            return "%s in template" % arg1[0]
+        self.checkScript(fn, (["foo", "bar"],))
+
+    def test_string_interpolation_with_too_few_arguments(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%s %s in template" % arg1
+
+        with self.assertRaisesRegex(RuntimeError, "Too few arguments for format string"):
+            fn("foo")
+
+    def test_string_interpolation_with_too_many_arguments(self):
+        @torch.jit.script
+        def fn(arg1: str, arg2: str) -> str:
+            return "%s in template" % (arg1, arg2)    # noqa: F507
+
+        with self.assertRaisesRegex(RuntimeError, "Too many arguments for format string"):
+            fn("foo", "bar")
+
+    def test_string_interpolation_with_unknown_format_specifier(self):
+        @torch.jit.script
+        def fn(arg1: str) -> str:
+            return "%a in template" % arg1    # noqa: F501
+
+        with self.assertRaisesRegex(RuntimeError, "The specifier %a is not supported in TorchScript format strings"):
+            fn("foo")

test/test_jit.py

@@ -30,6 +30,7 @@
 from jit.test_onnx_export import TestONNXExport  # noqa: F401
 from jit.test_with import TestWith  # noqa: F401
 from jit.test_enum import TestEnum  # noqa: F401
+from jit.test_string_formatting import TestStringFormatting  # noqa: F401
 from jit.test_profiler import TestProfiler  # noqa: F401
 from jit.test_slice import TestSlice  # noqa: F401
 from jit.test_warn import TestWarn  # noqa: F401

torch/csrc/jit/frontend/ir_emitter.cpp

@@ -3124,6 +3124,22 @@ struct to_ir {
     return std::make_shared<SimpleValue>(rpc_node_output);
   }
 
+  Value* emitBinaryOp(const TreeRef& tree) {
+    const auto& inputs = tree->trees();
+    auto kind = getNodeKind(tree->kind(), inputs.size());
+    auto overload = getOperatorOverload(tree->kind(), inputs.size());
+    auto named_values = getNamedValues(inputs, /*maybe_unpack=*/false);
+    if (tree->kind() == TK_IN) {
+      // For `in` the arguments are in reverse order (the object being
+      // checked is second)
+      std::iter_swap(named_values.begin() + 0, named_values.begin() + 1);
+    }
+    return asSimple(
+        makeMagic(
+            overload, std::make_shared<BuiltinFunction>(kind, at::nullopt))
+            ->call(tree->range(), method, named_values, {}, 0));
+  }
+
   Value* emitSimpleExpr(
       const TreeRef& tree,
       const TypePtr& type_hint = nullptr) {
@@ -3136,6 +3152,21 @@ struct to_ir {
         return emitBuiltinCall(
             tree->range(), *method.graph(), kind, named_values, {});
       }
+      case '%': {
+        auto lhs = emitSugaredExpr(Expr(tree->tree(0)), 0)
+                       ->asValue(tree->tree(0)->range(), method);
+        auto const& lhs_type = lhs->type();
+        if (lhs_type == StringType::get()) {
+          auto values = getValues(tree->trees(), /*maybe_unpack=*/false);
+          auto node = graph->create(aten::percentFormat, values, 1)
+                          ->setSourceRange(tree->range());
+          Value* output = graph->insertNode(node)->output();
+          output->setType(StringType::get());
+          return output;
+        } else {
+          return emitBinaryOp(tree);
+        }
+      }
       case TK_IN:
       case TK_POW:
       case TK_NE:
@@ -3148,28 +3179,12 @@ struct to_ir {
       case '/':
       case '+':
       case '-':
-      case '%':
       case '&':
       case '|':
       case '^':
       case TK_LSHIFT:
-      case TK_RSHIFT: {
-        const auto& inputs = tree->trees();
-        auto kind = getNodeKind(tree->kind(), inputs.size());
-        auto overload = getOperatorOverload(tree->kind(), inputs.size());
-        auto named_values = getNamedValues(inputs, /*maybe_unpack=*/false);
-
-        if (tree->kind() == TK_IN) {
-          // For `in` the arguments are in reverse order (the object being
-          // checked is second)
-          std::iter_swap(named_values.begin() + 0, named_values.begin() + 1);
-        }
-
-        return asSimple(
-            makeMagic(
-                overload, std::make_shared<BuiltinFunction>(kind, at::nullopt))
-                ->call(tree->range(), method, named_values, {}, 0));
-      }
+      case TK_RSHIFT:
+        return emitBinaryOp(tree);
       case TK_IS:
       case TK_ISNOT:
       case TK_AND:

torch/csrc/jit/runtime/register_prim_ops_fulljit.cpp

@@ -211,6 +211,13 @@ RegisterOperators reg(
            push(stack, c10::Device(pop(stack).toStringRef()));
          },
          aliasAnalysisFromSchema()),
+     Operator(
+         "aten::percentFormat(str self, ...) -> str",
+         [](Stack* stack) {
+           size_t num_inputs = pop(stack).toInt();
+           percentFormat(*stack, num_inputs);
+         },
+         aliasAnalysisFromSchema()),
      Operator(
          "aten::to.prim_other(Tensor(a) self, bool non_blocking=False, bool copy=False) -> Tensor(a|b)",
          [](Stack* stack) {