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First pass at plugin gen

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charles
2026-05-02 22:48:03 -07:00
parent 33449d00c8
commit 8ae8c5dfd3
8 changed files with 2765 additions and 203 deletions
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src/generator.rs
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use crate::proto_gen::google::protobuf::descriptor::{
DescriptorProto, EnumDescriptorProto, FieldDescriptorProto, FileDescriptorProto, FileDescriptorSet,
};
use crate::{ProtoAccessor, Result, RotoError};
use std::str;
pub fn to_pascal_case(s: &str) -> String {
s.split('_')
.map(|word| {
let mut chars = word.chars();
match chars.next() {
None => String::new(),
Some(f) => f.to_uppercase().collect::<String>() + chars.as_str(),
}
})
.collect()
}
fn map_type_to_rust_accessor(field_type: i32, label: i32) -> (String, String) {
if label == 3 {
// LABEL_REPEATED
return (
"crate::RepeatedFieldIterator<'a>".to_string(),
"self.0.iter_repeated(%d)".to_string(),
);
}
match field_type {
9 => (
"&'a str".to_string(),
"str::from_utf8(bytes).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // TYPE_STRING
1 => (
"f64".to_string(),
"f64::from_le_bytes(bytes.try_into().map_err(|_| RotoError::WireFormatViolation)?)".to_string(),
), // TYPE_DOUBLE
2 => (
"f32".to_string(),
"f32::from_le_bytes(bytes.try_into().map_err(|_| RotoError::WireFormatViolation)?)".to_string(),
), // TYPE_FLOAT
3 | 5 | 15 | 17 => (
"i32".to_string(),
"crate::read_varint(bytes).map(|(v, _)| v as i32).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // INT/SINT/SFIXED 32
4 | 6 | 13 => (
"u32".to_string(),
"crate::read_varint(bytes).map(|(v, _)| v as u32).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // UINT/FIXED 32
16 | 18 => (
"i64".to_string(),
"crate::read_varint(bytes).map(|(v, _)| v as i64).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // SINT/SFIXED 64
7 | 14 => (
"u64".to_string(),
"crate::read_varint(bytes).map(|(v, _)| v as u64).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // UINT/FIXED 64
8 => (
"bool".to_string(),
"crate::read_varint(bytes).map(|(v, _)| v != 0).map_err(|_| RotoError::WireFormatViolation)".to_string(),
), // TYPE_BOOL
11 | 12 => ("&'a [u8]".to_string(), "Ok(bytes)".to_string()), // MESSAGE/BYTES
_ => ("&'a [u8]".to_string(), "Ok(bytes)".to_string()),
}
}
fn map_type_to_rust_builder(field_type: i32) -> (String, String) {
match field_type {
9 => ("&str".to_string(), "write_string".to_string()),
5 | 17 => ("i32".to_string(), "write_int32".to_string()),
3 | 4 | 8 | 13 | 14 | 18 => ("i64".to_string(), "write_varint".to_string()),
7 | 15 => ("u32".to_string(), "write_fixed32".to_string()),
6 | 16 => ("u64".to_string(), "write_fixed64".to_string()),
11 | 12 => ("&[u8]".to_string(), "write_bytes".to_string()),
_ => ("&[u8]".to_string(), "write_bytes".to_string()),
}
}
pub fn generate_rust_code(set: &FileDescriptorSet) -> String {
let mut output = String::new();
output.push_str("use crate::{ProtoAccessor, ProtoBuilder, Result, RotoError};\n");
output.push_str("use std::str;\n\n");
for file_res in set.file() {
let (file_data, _) = file_res.expect("Failed to iterate file");
let file_proto = FileDescriptorProto::new(file_data).expect("Failed to parse FileDescriptorProto");
// Enums
for enum_res in file_proto.enum_type() {
let (enum_data, _) = enum_res.expect("Failed to iterate enum");
let enum_proto = EnumDescriptorProto::new(enum_data).expect("Failed to parse EnumDescriptorProto");
let enum_name = to_pascal_case(enum_proto.name().unwrap());
output.push_str(&format!(
"#[derive(Debug, Clone, Copy, PartialEq, Eq)]\n#[repr(i32)]\npub enum {} {{\n",
enum_name
));
let mut values = enum_proto.enum_value();
let mut variant_count = 0;
while let Some(val_res) = values.next() {
let (val_data, _) = val_res.expect("Failed to read enum value");
let accessor = ProtoAccessor::new(val_data).expect("Failed to parse EnumValueDescriptorProto");
let (name_bytes, _) = accessor.get_value(1).expect("Enum value name missing");
let name = str::from_utf8(name_bytes).expect("Enum value name invalid utf8");
let (num_bytes, _) = accessor.get_value(2).expect("Enum value number missing");
let (num, _) = crate::read_varint(num_bytes).expect("Enum value number invalid varint");
output.push_str(&format!(" {}, = {},\n", to_pascal_case(name), num));
variant_count += 1;
}
if variant_count == 0 {
output.push_str(" Unknown = 0,\n");
}
output.push_str("}\n\n");
output.push_str(&format!(
"impl {} {{\n pub fn from_i32(value: i32) -> Self {{\n match value {{\n",
enum_name
));
let mut values = enum_proto.enum_value();
while let Some(val_res) = values.next() {
let (val_data, _) = val_res.expect("Failed to read enum value");
let accessor = ProtoAccessor::new(val_data).expect("Failed to parse EnumValueDescriptorProto");
let (name_bytes, _) = accessor.get_value(1).expect("Enum value name missing");
let name = str::from_utf8(name_bytes).expect("Enum value name invalid utf8");
let (num_bytes, _) = accessor.get_value(2).expect("Enum value number missing");
let (num, _) = crate::read_varint(num_bytes).expect("Enum value number invalid varint");
output.push_str(&format!(" {} => {}::{},\n", num, enum_name, to_pascal_case(name)));
}
output.push_str(&format!(" _ => {}::Unknown,\n", enum_name));
output.push_str(" }\n }}\n}\n\n");
}
// Messages
for msg_res in file_proto.message_type() {
let (msg_data, _) = msg_res.expect("Failed to iterate message");
let msg_proto = DescriptorProto::new(msg_data).expect("Failed to parse DescriptorProto");
let msg_name = to_pascal_case(msg_proto.name().unwrap());
// Accessor
output.push_str(&format!(
"pub struct {}<'a>(ProtoAccessor<'a>);\n\nimpl<'a> {}<'a> {{\n",
msg_name, msg_name
));
output.push_str(&format!(
" pub fn new(data: &'a [u8]) -> Result<Self> {{\n Ok(Self(ProtoAccessor::new(data)?))\n }}\n\n"
));
for field_res in msg_proto.field() {
let (field_data, _) = field_res.expect("Failed to iterate field");
let field_proto = FieldDescriptorProto::new(field_data).expect("Failed to parse FieldDescriptorProto");
let field_name = field_proto.name().unwrap();
let tag = field_proto.number().unwrap();
let f_type = field_proto.field_type().unwrap() as i32;
let f_label = field_proto.label().unwrap() as i32;
let (rust_type, logic) = map_type_to_rust_accessor(f_type, f_label);
if f_label == 3 {
output.push_str(&format!(
" pub fn {}(&self) -> {} {{\n {}\n }}\n\n",
field_name, rust_type, logic.replace("%d", &tag.to_string())
));
} else {
output.push_str(&format!(
" pub fn {}(&self) -> Result<{}> {{\n let (bytes, _) = self.0.get_value({})?;\n {}\n }}\n\n",
field_name, rust_type, tag, logic
));
}
}
output.push_str("}\n\n");
// Builder
output.push_str(&format!(
"pub struct {}Builder<'b> {{\n builder: ProtoBuilder<'b>,\n}}\n\nimpl<'b> {}Builder<'b> {{\n",
msg_name, msg_name
));
output.push_str(&format!(
" pub fn builder(buf: &mut [u8]) -> {}Builder<'_> {{\n {}Builder {{\n builder: ProtoBuilder::new(buf),\n }}\n }}\n\n",
msg_name, msg_name
));
for field_res in msg_proto.field() {
let (field_data, _) = field_res.expect("Failed to iterate field");
let field_proto = FieldDescriptorProto::new(field_data).expect("Failed to parse FieldDescriptorProto");
let field_name = field_proto.name().unwrap();
let tag = field_proto.number().unwrap();
let f_type = field_proto.field_type().unwrap() as i32;
let (rust_type, method) = map_type_to_rust_builder(f_type);
output.push_str(&format!(
" pub fn {}(mut self, value: {}) -> Result<Self> {{\n self.builder.{}({}, value)?;\n Ok(self)\n }}\n\n",
field_name, rust_type, method, tag
));
}
output.push_str(&format!(
" pub fn finish(self) -> Result<&'b mut [u8]> {{\n self.builder.finish()\n }}\n}}\n\n"
));
}
}
output
}