be/src/gutil/strings/substitute.cc

// Copyright 2008 Google Inc.  All rights reserved.

#include "gutil/strings/substitute.h"

#include "common/logging.h"
#include <stdint.h>
#include <ostream>

// IWYU pragma: no_include <butil/macros.h>
#include "gutil/macros.h" // IWYU pragma: keep
#include "gutil/stl_util.h"
#include "gutil/strings/ascii_ctype.h"
#include "gutil/strings/escaping.h"

namespace strings {

using internal::SubstituteArg;

const SubstituteArg SubstituteArg::NoArg;

// Returns the number of args in arg_array which were passed explicitly
// to Substitute().
static int CountSubstituteArgs(const SubstituteArg* const* args_array) {
    int count = 0;
    while (args_array[count] != &SubstituteArg::NoArg) {
        ++count;
    }
    return count;
}

namespace internal {
int SubstitutedSize(StringPiece format, const SubstituteArg* const* args_array) {
    int size = 0;
    for (int i = 0; i < format.size(); i++) {
        if (format[i] == '$') {
            if (i + 1 >= format.size()) {
                LOG(DFATAL) << "Invalid strings::Substitute() format string: \"" << CEscape(format)
                            << "\".";
                return 0;
            } else if (ascii_isdigit(format[i + 1])) {
                int index = format[i + 1] - '0';
                if (args_array[index]->size() == -1) {
                    LOG(DFATAL) << "strings::Substitute format string invalid: asked for \"$"
                                << index << "\", but only " << CountSubstituteArgs(args_array)
                                << " args were given.  Full format string was: \""
                                << CEscape(format) << "\".";
                    return 0;
                }
                size += args_array[index]->size();
                ++i; // Skip next char.
            } else if (format[i + 1] == '$') {
                ++size;
                ++i; // Skip next char.
            } else {
                LOG(DFATAL) << "Invalid strings::Substitute() format string: \"" << CEscape(format)
                            << "\".";
                return 0;
            }
        } else {
            ++size;
        }
    }
    return size;
}

char* SubstituteToBuffer(StringPiece format, const SubstituteArg* const* args_array, char* target) {
    for (int i = 0; i < format.size(); i++) {
        if (format[i] == '$') {
            if (ascii_isdigit(format[i + 1])) {
                const SubstituteArg* src = args_array[format[i + 1] - '0'];
                memcpy(target, src->data(), src->size());
                target += src->size();
                ++i; // Skip next char.
            } else if (format[i + 1] == '$') {
                *target++ = '$';
                ++i; // Skip next char.
            }
        } else {
            *target++ = format[i];
        }
    }
    return target;
}

} // namespace internal

void SubstituteAndAppend(string* output, StringPiece format, const SubstituteArg& arg0,
                         const SubstituteArg& arg1, const SubstituteArg& arg2,
                         const SubstituteArg& arg3, const SubstituteArg& arg4,
                         const SubstituteArg& arg5, const SubstituteArg& arg6,
                         const SubstituteArg& arg7, const SubstituteArg& arg8,
                         const SubstituteArg& arg9) {
    const SubstituteArg* const args_array[] = {&arg0, &arg1, &arg2, &arg3, &arg4,  &arg5,
                                               &arg6, &arg7, &arg8, &arg9, nullptr};

    // Determine total size needed.
    int size = SubstitutedSize(format, args_array);
    if (size == 0) return;

    // Build the string.
    int original_size = output->size();
    STLStringResizeUninitialized(output, original_size + size);
    char* target = string_as_array(output) + original_size;

    target = SubstituteToBuffer(format, args_array, target);
    DCHECK_EQ(target - output->data(), output->size());
}

SubstituteArg::SubstituteArg(const void* value) {
    COMPILE_ASSERT(sizeof(scratch_) >= sizeof(value) * 2 + 2, fix_sizeof_scratch_);
    if (value == nullptr) {
        text_ = "NULL";
        size_ = strlen(text_);
    } else {
        char* ptr = scratch_ + sizeof(scratch_);
        uintptr_t num = reinterpret_cast<uintptr_t>(value);
        static const char kHexDigits[] = "0123456789abcdef";
        do {
            *--ptr = kHexDigits[num & 0xf];
            num >>= 4;
        } while (num != 0);
        *--ptr = 'x';
        *--ptr = '0';
        text_ = ptr;
        size_ = scratch_ + sizeof(scratch_) - ptr;
    }
}

} // namespace strings