Implementation:Alibaba MNN Protobuf Text Format H

Metadata

Attribute	Value
Implementation File	`3rd_party/protobuf/src/google/protobuf/text_format.h`
Line Count	687
Domains	Serialization, Debugging
Key Classes	`TextFormat`, `TextFormat::Printer`
Created	2026-02-10
Knowledge Sources	Repo, Doc

Overview

Human-readable text format serialization for protobuf messages. Provides both printing (message to text) and parsing (text to message) of protobuf data in a readable, editable format.

Usage note: Vendored dependency used internally by MNN for parsing protobuf-based model formats. Not directly imported by end users.

Description

The TextFormat class provides static utility methods and nested helper classes for converting protobuf messages to and from a human-readable text representation (sometimes called "text proto" or "pbtxt" format). Key components:

TextFormat::Print -- Converts a message to its text representation, writing to a string or output stream.
TextFormat::Parse -- Parses a text-format string into a message object.
TextFormat::Printer -- Configurable printer with options for single-line output, custom field value printers, truncation of long strings, and hiding unknown fields.
TextFormat::Parser -- Configurable parser with support for custom error collectors, allowing/disallowing unknown fields, and partial message parsing.
TextFormat::FieldValuePrinter -- Base class for custom per-field formatting (e.g., printing enums as integers, formatting byte fields as hex).

The text format is widely used for debugging, logging, configuration files (.pbtxt), and test assertions.

Usage

#include "google/protobuf/text_format.h"

Used for debugging output, configuration file parsing, and human-readable serialization.

Code Reference

class PROTOBUF_EXPORT TextFormat {
 public:
  // Simple static methods.
  static bool Print(const Message& message, io::ZeroCopyOutputStream* output);
  static bool PrintToString(const Message& message, std::string* output);
  static bool Parse(io::ZeroCopyInputStream* input, Message* output);
  static bool ParseFromString(const std::string& input, Message* output);

  // Configurable printer.
  class PROTOBUF_EXPORT Printer {
   public:
    Printer();

    bool Print(const Message& message, io::ZeroCopyOutputStream* output) const;
    bool PrintToString(const Message& message, std::string* output) const;

    void SetSingleLineMode(bool single_line_mode);
    void SetExpandAny(bool expand);
    void SetTruncateStringFieldLongerThan(int64_t max_length);
    void SetUseShortRepeatedPrimitives(bool use_short);

    // Register custom field value printers.
    bool RegisterFieldValuePrinter(
        const FieldDescriptor* field,
        const FieldValuePrinter* printer);
  };

  // Configurable parser.
  class PROTOBUF_EXPORT Parser {
   public:
    Parser();

    bool Parse(io::ZeroCopyInputStream* input, Message* output);
    bool ParseFromString(const std::string& input, Message* output);

    void AllowUnknownField(bool allow);
    void AllowPartialMessage(bool allow);
    void RecordErrorsTo(io::ErrorCollector* error_collector);
  };
};

I/O Contract

Direction	Type	Description
Input (Print)	`Message`	Populated protobuf message to render as text
Output (Print)	`std::string` / stream	Human-readable text proto representation
Input (Parse)	`std::string` / stream	Text proto format string to deserialize
Output (Parse)	`Message`	Populated message fields from parsed text

Usage Examples

// Print a message as human-readable text
std::string text;
google::protobuf::TextFormat::PrintToString(my_message, &text);
std::cout << text;

// Parse text format into a message
MyMessage msg;
google::protobuf::TextFormat::ParseFromString(
    "name: \"example\"\nid: 42\n", &msg);

// Single-line output for logging
google::protobuf::TextFormat::Printer printer;
printer.SetSingleLineMode(true);
std::string single_line;
printer.PrintToString(msg, &single_line);

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