This revision was automatically updated to reflect the committed changes.
Closed by commit rG16619e7139bd: [JSON] Facility to track position within an
object and report errors. (authored by sammccall).
Changed prior to commit:
https://reviews.llvm.org/D88103?vs=293864&id=293870#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D88103/new/
https://reviews.llvm.org/D88103
Files:
llvm/include/llvm/Support/JSON.h
llvm/lib/Support/JSON.cpp
llvm/unittests/Support/JSONTest.cpp
Index: llvm/unittests/Support/JSONTest.cpp
===================================================================
--- llvm/unittests/Support/JSONTest.cpp
+++ llvm/unittests/Support/JSONTest.cpp
@@ -8,6 +8,7 @@
#include "llvm/Support/JSON.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Testing/Support/Error.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
@@ -461,6 +462,17 @@
EXPECT_EQ(Pretty, StreamStuff(2));
}
+TEST(JSONTest, Path) {
+ Path::Root R("foo");
+ Path P = R, A = P.field("a"), B = P.field("b");
+ A.index(1).field("c").index(2).report("boom");
+ EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("boom at foo.a[1].c[2]"));
+ B.field("d").field("e").report("bam");
+ EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("bam at foo.b.d.e"));
+ P.report("oh no");
+ EXPECT_THAT_ERROR(R.getError(), FailedWithMessage("oh no when parsing foo"));
+}
+
} // namespace
} // namespace json
} // namespace llvm
Index: llvm/lib/Support/JSON.cpp
===================================================================
--- llvm/lib/Support/JSON.cpp
+++ llvm/lib/Support/JSON.cpp
@@ -7,7 +7,9 @@
//===---------------------------------------------------------------------===//
#include "llvm/Support/JSON.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ConvertUTF.h"
+#include "llvm/Support/Error.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <cctype>
@@ -199,6 +201,40 @@
llvm_unreachable("Unknown value kind");
}
+void Path::report(llvm::StringLiteral Msg) {
+ // Walk up to the root context, and count the number of segments.
+ unsigned Count = 0;
+ const Path *P;
+ for (P = this; P->Parent != nullptr; P = P->Parent)
+ ++Count;
+ Path::Root *R = P->Seg.root();
+ // Fill in the error message and copy the path (in reverse order).
+ R->ErrorMessage = Msg;
+ R->ErrorPath.resize(Count);
+ auto It = R->ErrorPath.begin();
+ for (P = this; P->Parent != nullptr; P = P->Parent)
+ *It++ = P->Seg;
+}
+
+Error Path::Root::getError() const {
+ std::string S;
+ raw_string_ostream OS(S);
+ OS << (ErrorMessage.empty() ? "invalid JSON contents" : ErrorMessage);
+ if (ErrorPath.empty()) {
+ if (!Name.empty())
+ OS << " when parsing " << Name;
+ } else {
+ OS << " at " << (Name.empty() ? "(root)" : Name);
+ for (const Path::Segment &S : llvm::reverse(ErrorPath)) {
+ if (S.isField())
+ OS << '.' << S.field();
+ else
+ OS << '[' << S.index() << ']';
+ }
+ }
+ return createStringError(llvm::inconvertibleErrorCode(), OS.str());
+}
+
namespace {
// Simple recursive-descent JSON parser.
class Parser {
Index: llvm/include/llvm/Support/JSON.h
===================================================================
--- llvm/include/llvm/Support/JSON.h
+++ llvm/include/llvm/Support/JSON.h
@@ -557,6 +557,75 @@
return M.erase(ObjectKey(K));
}
+/// A "cursor" marking a position within a Value.
+/// The Value is a tree, and this is the path from the root to the current node.
+/// This is used to associate errors with particular subobjects.
+class Path {
+public:
+ class Root;
+
+ /// Records that the value at the current path is invalid.
+ /// Message is e.g. "expected number" and becomes part of the final error.
+ /// This overwrites any previously written error message in the root.
+ void report(llvm::StringLiteral Message);
+
+ /// The root may be treated as a Path.
+ Path(Root &R) : Parent(nullptr), Seg(&R) {}
+ /// Derives a path for an array element: this[Index]
+ Path index(unsigned Index) const { return Path(this, Segment(Index)); }
+ /// Derives a path for an object field: this.Field
+ Path field(StringRef Field) const { return Path(this, Segment(Field)); }
+
+private:
+ /// One element in a JSON path: an object field (.foo) or array index [27].
+ /// Exception: the root Path encodes a pointer to the Path::Root.
+ class Segment {
+ uintptr_t Pointer;
+ unsigned Offset;
+
+ public:
+ Segment() = default;
+ Segment(Root *R) : Pointer(reinterpret_cast<uintptr_t>(R)) {}
+ Segment(llvm::StringRef Field)
+ : Pointer(reinterpret_cast<uintptr_t>(Field.data())),
+ Offset(static_cast<unsigned>(Field.size())) {}
+ Segment(unsigned Index) : Pointer(0), Offset(Index) {}
+
+ bool isField() const { return Pointer != 0; }
+ StringRef field() const {
+ return StringRef(reinterpret_cast<const char *>(Pointer), Offset);
+ }
+ unsigned index() const { return Offset; }
+ Root *root() const { return reinterpret_cast<Root *>(Pointer); }
+ };
+
+ const Path *Parent;
+ Segment Seg;
+
+ Path(const Path *Parent, Segment S) : Parent(Parent), Seg(S) {}
+};
+
+/// The root is the trivial Path to the root value.
+/// It also stores the latest reported error and the path where it occurred.
+class Path::Root {
+ llvm::StringRef Name;
+ llvm::StringLiteral ErrorMessage;
+ std::vector<Path::Segment> ErrorPath; // Only valid in error state. Reversed.
+
+ friend void Path::report(llvm::StringLiteral Message);
+
+public:
+ Root(llvm::StringRef Name = "") : Name(Name), ErrorMessage("") {}
+ // No copy/move allowed as there are incoming pointers.
+ Root(Root &&) = delete;
+ Root &operator=(Root &&) = delete;
+ Root(const Root &) = delete;
+ Root &operator=(const Root &) = delete;
+
+ /// Returns the last error reported, or else a generic error.
+ Error getError() const;
+};
+
// Standard deserializers are provided for primitive types.
// See comments on Value.
inline bool fromJSON(const Value &E, std::string &Out) {
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