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| 1 | +// Copyright 2020-2026 Buf Technologies, Inc. |
| 2 | +// |
| 3 | +// Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +// you may not use this file except in compliance with the License. |
| 5 | +// You may obtain a copy of the License at |
| 6 | +// |
| 7 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +// |
| 9 | +// Unless required by applicable law or agreed to in writing, software |
| 10 | +// distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +// See the License for the specific language governing permissions and |
| 13 | +// limitations under the License. |
| 14 | + |
| 15 | +package assembler |
| 16 | + |
| 17 | +import ( |
| 18 | + "encoding/binary" |
| 19 | + "encoding/hex" |
| 20 | + "math" |
| 21 | + "strings" |
| 22 | + "unicode" |
| 23 | + |
| 24 | + "github.com/bufbuild/protocompile/experimental/id" |
| 25 | + "github.com/bufbuild/protocompile/experimental/internal/protoscope/ast" |
| 26 | + "github.com/bufbuild/protocompile/experimental/seq" |
| 27 | + "github.com/bufbuild/protocompile/experimental/token" |
| 28 | + "github.com/bufbuild/protocompile/experimental/token/keyword" |
| 29 | +) |
| 30 | + |
| 31 | +// Assemble translates a protoscope AST into Protobuf wire format. |
| 32 | +func Assemble(file *ast.File) []byte { |
| 33 | + a := &assembler{} |
| 34 | + for decl := range seq.Values(file.Decls()) { |
| 35 | + a.assembleDecl(decl, false) |
| 36 | + } |
| 37 | + return a.buf |
| 38 | +} |
| 39 | + |
| 40 | +type assembler struct { |
| 41 | + buf []byte |
| 42 | +} |
| 43 | + |
| 44 | +func (a *assembler) assembleDecl(decl ast.DeclAny, inBlock bool) { |
| 45 | + switch decl.Kind() { |
| 46 | + case ast.DeclKindField: |
| 47 | + a.assembleField(id.Wrap(decl.Context(), id.ID[ast.Field](decl.ID().Value()))) |
| 48 | + case ast.DeclKindLiteral: |
| 49 | + a.assembleLiteral(id.Wrap(decl.Context(), id.ID[ast.Literal](decl.ID().Value())), inBlock) |
| 50 | + case ast.DeclKindBlock: |
| 51 | + a.assembleBlock(id.Wrap(decl.Context(), id.ID[ast.Block](decl.ID().Value())), inBlock) |
| 52 | + } |
| 53 | +} |
| 54 | + |
| 55 | +func (a *assembler) assembleField(f ast.Field) { |
| 56 | + tag, _ := f.Tag().AsNumber().Int() |
| 57 | + wireType := uint64(0) |
| 58 | + val := f.Value() |
| 59 | + if !val.IsZero() { |
| 60 | + switch val.Kind() { |
| 61 | + case ast.DeclKindBlock: |
| 62 | + block := id.Wrap(val.Context(), id.ID[ast.Block](val.ID().Value())) |
| 63 | + if block.Token().Keyword() == keyword.Bang { |
| 64 | + wireType = 3 // SGROUP |
| 65 | + } else { |
| 66 | + wireType = 2 // LEN |
| 67 | + } |
| 68 | + case ast.DeclKindLiteral: |
| 69 | + lit := id.Wrap(val.Context(), id.ID[ast.Literal](val.ID().Value())) |
| 70 | + if lit.Token().Kind() == token.String { |
| 71 | + wireType = 2 // LEN |
| 72 | + } else if lit.Token().Kind() == token.Number { |
| 73 | + num := lit.Token().AsNumber() |
| 74 | + suffix := num.Suffix().Text() |
| 75 | + switch suffix { |
| 76 | + case "i64", "f64": |
| 77 | + wireType = 1 // I64 |
| 78 | + case "i32", "f32": |
| 79 | + wireType = 5 // I32 |
| 80 | + default: |
| 81 | + if num.IsFloat() { |
| 82 | + wireType = 1 // I64 (double) |
| 83 | + } |
| 84 | + } |
| 85 | + } |
| 86 | + } |
| 87 | + } |
| 88 | + |
| 89 | + // Override with explicit wire type hint. |
| 90 | + switch f.WireType().Text() { |
| 91 | + case "VARINT": |
| 92 | + wireType = 0 |
| 93 | + case "I64": |
| 94 | + wireType = 1 |
| 95 | + case "LEN": |
| 96 | + wireType = 2 |
| 97 | + case "SGROUP": |
| 98 | + wireType = 3 |
| 99 | + case "EGROUP": |
| 100 | + wireType = 4 |
| 101 | + case "I32": |
| 102 | + wireType = 5 |
| 103 | + } |
| 104 | + |
| 105 | + a.writeVarint(tag<<3 | wireType) |
| 106 | + |
| 107 | + if wireType == 4 { // EGROUP |
| 108 | + return |
| 109 | + } |
| 110 | + |
| 111 | + if wireType == 3 { // SGROUP |
| 112 | + a.assembleDecl(val, false) |
| 113 | + a.writeVarint(tag<<3 | 4) // Emit matching EGROUP |
| 114 | + return |
| 115 | + } |
| 116 | + |
| 117 | + if wireType == 2 { // LEN |
| 118 | + // Length-delimited fields must be prefixed by their length. |
| 119 | + // Some values (blocks and strings) are self-length-delimited. |
| 120 | + isSelfDelimited := false |
| 121 | + if !val.IsZero() && val.Kind() == ast.DeclKindBlock { |
| 122 | + isSelfDelimited = true |
| 123 | + } |
| 124 | + if !val.IsZero() && val.Kind() == ast.DeclKindLiteral { |
| 125 | + lit := id.Wrap(val.Context(), id.ID[ast.Literal](val.ID().Value())) |
| 126 | + if lit.Token().Kind() == token.String { |
| 127 | + isSelfDelimited = true |
| 128 | + } |
| 129 | + } |
| 130 | + |
| 131 | + if isSelfDelimited { |
| 132 | + a.assembleDecl(val, false) |
| 133 | + } else { |
| 134 | + sub := &assembler{} |
| 135 | + sub.assembleDecl(val, false) |
| 136 | + a.writeVarint(uint64(len(sub.buf))) |
| 137 | + a.buf = append(a.buf, sub.buf...) |
| 138 | + } |
| 139 | + return |
| 140 | + } |
| 141 | + |
| 142 | + a.assembleDecl(val, false) |
| 143 | +} |
| 144 | + |
| 145 | +func (a *assembler) assembleLiteral(l ast.Literal, inBlock bool) { |
| 146 | + tok := l.Token() |
| 147 | + switch tok.Keyword() { |
| 148 | + case keyword.True: |
| 149 | + a.writeVarint(1) |
| 150 | + return |
| 151 | + case keyword.False: |
| 152 | + a.writeVarint(0) |
| 153 | + return |
| 154 | + } |
| 155 | + |
| 156 | + switch tok.Kind() { |
| 157 | + case token.Number: |
| 158 | + // Check for suffix hints |
| 159 | + num := tok.AsNumber() |
| 160 | + suffix := num.Suffix().Text() |
| 161 | + switch suffix { |
| 162 | + case "i32": |
| 163 | + var buf [4]byte |
| 164 | + if num.IsFloat() { |
| 165 | + f, _ := num.Float() |
| 166 | + binary.LittleEndian.PutUint32(buf[:], math.Float32bits(float32(f))) |
| 167 | + } else { |
| 168 | + v, _ := num.Int() |
| 169 | + binary.LittleEndian.PutUint32(buf[:], uint32(v)) |
| 170 | + } |
| 171 | + a.buf = append(a.buf, buf[:]...) |
| 172 | + case "f32": |
| 173 | + f, _ := num.Float() |
| 174 | + var buf [4]byte |
| 175 | + binary.LittleEndian.PutUint32(buf[:], math.Float32bits(float32(f))) |
| 176 | + a.buf = append(a.buf, buf[:]...) |
| 177 | + case "i64": |
| 178 | + var buf [8]byte |
| 179 | + if num.IsFloat() { |
| 180 | + f, _ := num.Float() |
| 181 | + binary.LittleEndian.PutUint64(buf[:], math.Float64bits(f)) |
| 182 | + } else { |
| 183 | + v, _ := num.Int() |
| 184 | + binary.LittleEndian.PutUint64(buf[:], v) |
| 185 | + } |
| 186 | + a.buf = append(a.buf, buf[:]...) |
| 187 | + case "f64": |
| 188 | + f, _ := num.Float() |
| 189 | + var buf [8]byte |
| 190 | + binary.LittleEndian.PutUint64(buf[:], math.Float64bits(f)) |
| 191 | + a.buf = append(a.buf, buf[:]...) |
| 192 | + case "z": |
| 193 | + v := num.Value().Int(nil).Int64() |
| 194 | + // Zigzag encoding: (n << 1) ^ (n >> 63) |
| 195 | + zigzag := uint64((v << 1) ^ (v >> 63)) |
| 196 | + a.writeVarint(zigzag) |
| 197 | + default: |
| 198 | + if num.IsFloat() { |
| 199 | + f, _ := num.Float() |
| 200 | + var buf [8]byte |
| 201 | + binary.LittleEndian.PutUint64(buf[:], math.Float64bits(f)) |
| 202 | + a.buf = append(a.buf, buf[:]...) |
| 203 | + } else { |
| 204 | + v, _ := num.Int() |
| 205 | + a.writeVarint(v) |
| 206 | + } |
| 207 | + } |
| 208 | + case token.String: |
| 209 | + open, _ := tok.AsString().Quotes() |
| 210 | + isHex := open.Text() == "`" |
| 211 | + var contentBytes []byte |
| 212 | + if isHex { |
| 213 | + // Decode hex string |
| 214 | + var sb strings.Builder |
| 215 | + for _, r := range tok.AsString().Text() { |
| 216 | + if !unicode.IsSpace(r) { |
| 217 | + sb.WriteRune(r) |
| 218 | + } |
| 219 | + } |
| 220 | + var err error |
| 221 | + contentBytes, err = hex.DecodeString(sb.String()) |
| 222 | + if err != nil { |
| 223 | + // Fallback to raw string text if decoding fails |
| 224 | + contentBytes = []byte(tok.AsString().Text()) |
| 225 | + } |
| 226 | + } else { |
| 227 | + contentBytes = []byte(tok.AsString().Text()) |
| 228 | + } |
| 229 | + |
| 230 | + if inBlock { |
| 231 | + a.buf = append(a.buf, contentBytes...) |
| 232 | + } else { |
| 233 | + a.writeVarint(uint64(len(contentBytes))) |
| 234 | + a.buf = append(a.buf, contentBytes...) |
| 235 | + } |
| 236 | + } |
| 237 | +} |
| 238 | + |
| 239 | +func (a *assembler) assembleBlock(b ast.Block, _ bool) { |
| 240 | + tok := b.Token() |
| 241 | + switch tok.Keyword() { |
| 242 | + case keyword.LBracket, keyword.Brackets, keyword.LBrace, keyword.Braces: |
| 243 | + // Length-prefixed block |
| 244 | + sub := &assembler{} |
| 245 | + for decl := range seq.Values(b.Decls()) { |
| 246 | + sub.assembleDecl(decl, true) |
| 247 | + } |
| 248 | + a.writeVarint(uint64(len(sub.buf))) |
| 249 | + a.buf = append(a.buf, sub.buf...) |
| 250 | + case keyword.Bang: |
| 251 | + // Group content (no length prefix) |
| 252 | + for decl := range seq.Values(b.Decls()) { |
| 253 | + a.assembleDecl(decl, false) |
| 254 | + } |
| 255 | + } |
| 256 | +} |
| 257 | + |
| 258 | +func (a *assembler) writeVarint(v uint64) { |
| 259 | + var buf [10]byte |
| 260 | + n := binary.PutUvarint(buf[:], v) |
| 261 | + a.buf = append(a.buf, buf[:n]...) |
| 262 | +} |
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