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authorRalf Luther <luther.ralf@gmail.com>2019-03-27 20:23:17 +0000
committerGerrit Code Review <gerrit2@aicp-server-3>2019-03-27 20:23:17 +0000
commit1ce3a9d272e564b22a1333a1e36a3d3ab7cfab01 (patch)
tree391382eadd4fec5bb480f2e8934fa352770221d1 /clang-r353983/include/llvm/Support/FormatVariadic.h
parentd1d48b140bafaa8a50107292f5fce95562575765 (diff)
parent4f56932d3416ac03f646bc1a611b3135fec2fe08 (diff)
Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0
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+//===- FormatVariadic.h - Efficient type-safe string formatting --*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the formatv() function which can be used with other LLVM
+// subsystems to provide printf-like formatting, but with improved safety and
+// flexibility. The result of `formatv` is an object which can be streamed to
+// a raw_ostream or converted to a std::string or llvm::SmallString.
+//
+// // Convert to std::string.
+// std::string S = formatv("{0} {1}", 1234.412, "test").str();
+//
+// // Convert to llvm::SmallString
+// SmallString<8> S = formatv("{0} {1}", 1234.412, "test").sstr<8>();
+//
+// // Stream to an existing raw_ostream.
+// OS << formatv("{0} {1}", 1234.412, "test");
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_FORMATVARIADIC_H
+#define LLVM_SUPPORT_FORMATVARIADIC_H
+
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/FormatCommon.h"
+#include "llvm/Support/FormatProviders.h"
+#include "llvm/Support/FormatVariadicDetails.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstddef>
+#include <string>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+namespace llvm {
+
+enum class ReplacementType { Empty, Format, Literal };
+
+struct ReplacementItem {
+ ReplacementItem() = default;
+ explicit ReplacementItem(StringRef Literal)
+ : Type(ReplacementType::Literal), Spec(Literal) {}
+ ReplacementItem(StringRef Spec, size_t Index, size_t Align, AlignStyle Where,
+ char Pad, StringRef Options)
+ : Type(ReplacementType::Format), Spec(Spec), Index(Index), Align(Align),
+ Where(Where), Pad(Pad), Options(Options) {}
+
+ ReplacementType Type = ReplacementType::Empty;
+ StringRef Spec;
+ size_t Index = 0;
+ size_t Align = 0;
+ AlignStyle Where = AlignStyle::Right;
+ char Pad;
+ StringRef Options;
+};
+
+class formatv_object_base {
+protected:
+ // The parameters are stored in a std::tuple, which does not provide runtime
+ // indexing capabilities. In order to enable runtime indexing, we use this
+ // structure to put the parameters into a std::vector. Since the parameters
+ // are not all the same type, we use some type-erasure by wrapping the
+ // parameters in a template class that derives from a non-template superclass.
+ // Essentially, we are converting a std::tuple<Derived<Ts...>> to a
+ // std::vector<Base*>.
+ struct create_adapters {
+ template <typename... Ts>
+ std::vector<detail::format_adapter *> operator()(Ts &... Items) {
+ return std::vector<detail::format_adapter *>{&Items...};
+ }
+ };
+
+ StringRef Fmt;
+ std::vector<detail::format_adapter *> Adapters;
+ std::vector<ReplacementItem> Replacements;
+
+ static bool consumeFieldLayout(StringRef &Spec, AlignStyle &Where,
+ size_t &Align, char &Pad);
+
+ static std::pair<ReplacementItem, StringRef>
+ splitLiteralAndReplacement(StringRef Fmt);
+
+public:
+ formatv_object_base(StringRef Fmt, std::size_t ParamCount)
+ : Fmt(Fmt), Replacements(parseFormatString(Fmt)) {
+ Adapters.reserve(ParamCount);
+ }
+
+ formatv_object_base(formatv_object_base const &rhs) = delete;
+
+ formatv_object_base(formatv_object_base &&rhs)
+ : Fmt(std::move(rhs.Fmt)),
+ Adapters(), // Adapters are initialized by formatv_object
+ Replacements(std::move(rhs.Replacements)) {
+ Adapters.reserve(rhs.Adapters.size());
+ };
+
+ void format(raw_ostream &S) const {
+ for (auto &R : Replacements) {
+ if (R.Type == ReplacementType::Empty)
+ continue;
+ if (R.Type == ReplacementType::Literal) {
+ S << R.Spec;
+ continue;
+ }
+ if (R.Index >= Adapters.size()) {
+ S << R.Spec;
+ continue;
+ }
+
+ auto W = Adapters[R.Index];
+
+ FmtAlign Align(*W, R.Where, R.Align, R.Pad);
+ Align.format(S, R.Options);
+ }
+ }
+ static std::vector<ReplacementItem> parseFormatString(StringRef Fmt);
+
+ static Optional<ReplacementItem> parseReplacementItem(StringRef Spec);
+
+ std::string str() const {
+ std::string Result;
+ raw_string_ostream Stream(Result);
+ Stream << *this;
+ Stream.flush();
+ return Result;
+ }
+
+ template <unsigned N> SmallString<N> sstr() const {
+ SmallString<N> Result;
+ raw_svector_ostream Stream(Result);
+ Stream << *this;
+ return Result;
+ }
+
+ template <unsigned N> operator SmallString<N>() const { return sstr<N>(); }
+
+ operator std::string() const { return str(); }
+};
+
+template <typename Tuple> class formatv_object : public formatv_object_base {
+ // Storage for the parameter adapters. Since the base class erases the type
+ // of the parameters, we have to own the storage for the parameters here, and
+ // have the base class store type-erased pointers into this tuple.
+ Tuple Parameters;
+
+public:
+ formatv_object(StringRef Fmt, Tuple &&Params)
+ : formatv_object_base(Fmt, std::tuple_size<Tuple>::value),
+ Parameters(std::move(Params)) {
+ Adapters = apply_tuple(create_adapters(), Parameters);
+ }
+
+ formatv_object(formatv_object const &rhs) = delete;
+
+ formatv_object(formatv_object &&rhs)
+ : formatv_object_base(std::move(rhs)),
+ Parameters(std::move(rhs.Parameters)) {
+ Adapters = apply_tuple(create_adapters(), Parameters);
+ }
+};
+
+// Format text given a format string and replacement parameters.
+//
+// ===General Description===
+//
+// Formats textual output. `Fmt` is a string consisting of one or more
+// replacement sequences with the following grammar:
+//
+// rep_field ::= "{" [index] ["," layout] [":" format] "}"
+// index ::= <non-negative integer>
+// layout ::= [[[char]loc]width]
+// format ::= <any string not containing "{" or "}">
+// char ::= <any character except "{" or "}">
+// loc ::= "-" | "=" | "+"
+// width ::= <positive integer>
+//
+// index - A non-negative integer specifying the index of the item in the
+// parameter pack to print. Any other value is invalid.
+// layout - A string controlling how the field is laid out within the available
+// space.
+// format - A type-dependent string used to provide additional options to
+// the formatting operation. Refer to the documentation of the
+// various individual format providers for per-type options.
+// char - The padding character. Defaults to ' ' (space). Only valid if
+// `loc` is also specified.
+// loc - Where to print the formatted text within the field. Only valid if
+// `width` is also specified.
+// '-' : The field is left aligned within the available space.
+// '=' : The field is centered within the available space.
+// '+' : The field is right aligned within the available space (this
+// is the default).
+// width - The width of the field within which to print the formatted text.
+// If this is less than the required length then the `char` and `loc`
+// fields are ignored, and the field is printed with no leading or
+// trailing padding. If this is greater than the required length,
+// then the text is output according to the value of `loc`, and padded
+// as appropriate on the left and/or right by `char`.
+//
+// ===Special Characters===
+//
+// The characters '{' and '}' are reserved and cannot appear anywhere within a
+// replacement sequence. Outside of a replacement sequence, in order to print
+// a literal '{' or '}' it must be doubled -- "{{" to print a literal '{' and
+// "}}" to print a literal '}'.
+//
+// ===Parameter Indexing===
+// `index` specifies the index of the parameter in the parameter pack to format
+// into the output. Note that it is possible to refer to the same parameter
+// index multiple times in a given format string. This makes it possible to
+// output the same value multiple times without passing it multiple times to the
+// function. For example:
+//
+// formatv("{0} {1} {0}", "a", "bb")
+//
+// would yield the string "abba". This can be convenient when it is expensive
+// to compute the value of the parameter, and you would otherwise have had to
+// save it to a temporary.
+//
+// ===Formatter Search===
+//
+// For a given parameter of type T, the following steps are executed in order
+// until a match is found:
+//
+// 1. If the parameter is of class type, and inherits from format_adapter,
+// Then format() is invoked on it to produce the formatted output. The
+// implementation should write the formatted text into `Stream`.
+// 2. If there is a suitable template specialization of format_provider<>
+// for type T containing a method whose signature is:
+// void format(const T &Obj, raw_ostream &Stream, StringRef Options)
+// Then this method is invoked as described in Step 1.
+// 3. If an appropriate operator<< for raw_ostream exists, it will be used.
+// For this to work, (raw_ostream& << const T&) must return raw_ostream&.
+//
+// If a match cannot be found through either of the above methods, a compiler
+// error is generated.
+//
+// ===Invalid Format String Handling===
+//
+// In the case of a format string which does not match the grammar described
+// above, the output is undefined. With asserts enabled, LLVM will trigger an
+// assertion. Otherwise, it will try to do something reasonable, but in general
+// the details of what that is are undefined.
+//
+template <typename... Ts>
+inline auto formatv(const char *Fmt, Ts &&... Vals) -> formatv_object<decltype(
+ std::make_tuple(detail::build_format_adapter(std::forward<Ts>(Vals))...))> {
+ using ParamTuple = decltype(
+ std::make_tuple(detail::build_format_adapter(std::forward<Ts>(Vals))...));
+ return formatv_object<ParamTuple>(
+ Fmt,
+ std::make_tuple(detail::build_format_adapter(std::forward<Ts>(Vals))...));
+}
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_FORMATVARIADIC_H