Split useful helper code out of MergeOperationView into a separate li…

…b. (#443)

Closes #443

COPYBARA_INTEGRATE_REVIEW=#443 from google-research:literal_operator_view@winterrowd c76e017
PiperOrigin-RevId: 433783822

src/frontends/sql/testing/BUILD

@@ -25,6 +25,7 @@ cc_library(
     hdrs = ["merge_operation_view.h"],
     visibility = ["//src/frontends/sql:__subpackages__"],
     deps = [
+        ":operation_view_utils",
         "//src/common/logging",
         "//src/frontends/sql:decoder_context",
         "//src/ir:module",
@@ -45,3 +46,14 @@ cc_library(
         "//src/ir:value",
     ],
 )
+
+cc_library(
+    name = "operation_view_utils",
+    testonly = True,
+    srcs = ["operation_view_utils.cc"],
+    hdrs = ["operation_view_utils.h"],
+    deps = [
+        "//src/ir:value",
+        "@absl//absl/strings",
+    ],
+)

src/frontends/sql/testing/merge_operation_view.h

@@ -17,12 +17,11 @@
 #ifndef SRC_FRONTENDS_SQL_TESTING_MERGE_OPERATION_VIEW_H_
 #define SRC_FRONTENDS_SQL_TESTING_MERGE_OPERATION_VIEW_H_
 
-#include "absl/strings/match.h"
-#include "absl/strings/numbers.h"
 #include "src/common/logging/logging.h"
 #include "src/frontends/sql/decoder_context.h"
 #include "src/ir/module.h"
 #include "src/ir/operator.h"
+#include "src/frontends/sql/testing/operation_view_utils.h"
 
 namespace raksha::frontends::sql::testing {
 
@@ -47,43 +46,6 @@ class MergeOperationView {
   }
 
  private:
-  static std::optional<uint64_t> ExtractIdxAfterPrefix(
-      absl::string_view str, absl::string_view prefix) {
-    if (!absl::StartsWith(str, prefix)) return std::nullopt;
-    uint64_t result = 0;
-    std::string index_str(str.substr(prefix.size()));
-    if (!absl::SimpleAtoi(index_str, &result)) return std::nullopt;
-    return result;
-  }
-
-  static std::vector<ir::Value> GetVecWithPrefix(ir::NamedValueMap map,
-                                                 absl::string_view prefix) {
-    uint64_t inferred_vec_length = 0;
-
-    // The numbering of inputs should be dense. Thus, we can find the largest
-    // index with the given prefix, add one to it, and consider that the
-    // length of the vector.
-    for (auto &[key, value] : map) {
-      if (std::optional<uint64_t> opt_idx =
-              ExtractIdxAfterPrefix(key, prefix)) {
-        inferred_vec_length = std::max(inferred_vec_length, *opt_idx + 1);
-      }
-    }
-
-    // For each item with the prefix up to the inferred length, get the value
-    // and put it in the vector. If the numbering is not dense as we expect,
-    // fail.
-    std::vector<ir::Value> result;
-    result.reserve(inferred_vec_length);
-    for (uint64_t i = 0; i < inferred_vec_length; ++i) {
-      auto find_result = map.find(absl::StrCat(prefix, i));
-      CHECK(find_result != map.end())
-          << "Found a hole in the key numbering: " << find_result->first;
-      result.push_back(find_result->second);
-    }
-    return result;
-  }
-
   const ir::Operation *merge_operation_;
 };
 

src/frontends/sql/testing/operation_view_utils.cc

@@ -0,0 +1,45 @@
+#include "operation_view_utils.h"
+
+#include "absl/strings/match.h"
+#include "absl/strings/numbers.h"
+
+namespace raksha::frontends::sql::testing {
+
+std::optional<uint64_t> ExtractIdxAfterPrefix(
+    absl::string_view str, absl::string_view prefix) {
+  if (!absl::StartsWith(str, prefix)) return std::nullopt;
+  uint64_t result = 0;
+  std::string index_str(str.substr(prefix.size()));
+  if (!absl::SimpleAtoi(index_str, &result)) return std::nullopt;
+  return result;
+}
+
+std::vector<ir::Value> GetVecWithPrefix(const ir::NamedValueMap &map,
+                                               absl::string_view prefix) {
+  uint64_t inferred_vec_length = 0;
+
+  // The numbering of inputs should be dense. Thus, we can find the largest
+  // index with the given prefix, add one to it, and consider that the
+  // length of the vector.
+  for (auto &[key, value] : map) {
+    if (std::optional<uint64_t> opt_idx =
+            ExtractIdxAfterPrefix(key, prefix)) {
+      inferred_vec_length = std::max(inferred_vec_length, *opt_idx + 1);
+    }
+  }
+
+  // For each item with the prefix up to the inferred length, get the value
+  // and put it in the vector. If the numbering is not dense as we expect,
+  // fail.
+  std::vector<ir::Value> result;
+  result.reserve(inferred_vec_length);
+  for (uint64_t i = 0; i < inferred_vec_length; ++i) {
+    auto find_result = map.find(absl::StrCat(prefix, i));
+    CHECK(find_result != map.end())
+        << "Found a hole in the key numbering: " << find_result->first;
+    result.push_back(find_result->second);
+  }
+  return result;
+}
+
+}  // namespace raksha::frontends::sql::testing

src/frontends/sql/testing/operation_view_utils.h

@@ -0,0 +1,31 @@
+#ifndef SRC_FRONTENDS_SQL_TESTING_OPERATION_VIEW_UTILS_H_
+#define SRC_FRONTENDS_SQL_TESTING_OPERATION_VIEW_UTILS_H_
+
+#include <cstdint>
+#include <optional>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "src/ir/value.h"
+
+namespace raksha::frontends::sql::testing {
+
+// This helper expects that the provided `str` is of the form `prefix_[0-9]+`.
+// This function skips past the prefix, interprets the number as an unsigned
+// int, and returns it. If any of those assumptions are not met, it returns
+// std::nullopt instead.
+std::optional<uint64_t> ExtractIdxAfterPrefix(
+      absl::string_view str, absl::string_view prefix);
+
+// This method assumes that, within the given `NamedValueMap`, there are a
+// subset of elements that start with some prefix `prefix` and end with a
+// numeric index. Further, it assumes that those indicies are densely
+// clustered and starting at 0, such that they can be described as an array.
+// This method produces a `vector` from the values with that prefix, with the
+// trailing numeric suffixes being translated into positions in the resulting
+// vector. If the density assumption is not met, this method asserts.
+std::vector<ir::Value> GetVecWithPrefix(const ir::NamedValueMap &map,
+                                               absl::string_view prefix);
+}  // namespace raksha::frontends::sql::testing
+
+#endif  // SRC_FRONTENDS_SQL_TESTING_OPERATION_VIEW_UTILS_H_