feat: define default types during decode

packages/protons-benchmark/src/protons/bench.ts

@@ -159,7 +159,9 @@ export namespace Yo {
           writer.ldelim()
         }
       }, (reader, length) => {
-        const obj: any = {}
+        const obj: any = {
+          lol: []
+        }
 
         const end = length == null ? reader.len : reader.pos + length
 
@@ -168,7 +170,6 @@ export namespace Yo {
 
           switch (tag >>> 3) {
             case 1:
-              obj.lol = obj.lol ?? []
               obj.lol.push(FOO.codec().decode(reader))
               break
             default:
@@ -177,12 +178,6 @@ export namespace Yo {
           }
         }
 
-        obj.lol = obj.lol ?? []
-
-        if (obj.lol == null) {
-          throw new Error('Protocol error: value for required field "lol" was not found in protobuf')
-        }
-
         return obj
       })
     }
@@ -230,7 +225,9 @@ export namespace Lol {
           writer.ldelim()
         }
       }, (reader, length) => {
-        const obj: any = {}
+        const obj: any = {
+          b: undefined
+        }
 
         const end = length == null ? reader.len : reader.pos + length
 

packages/protons-runtime/src/index.ts

@@ -180,12 +180,12 @@ export interface Reader {
   double: () => number
 
   /**
-   * Reads a sequence of bytes preceeded by its length as a varint
+   * Reads a sequence of bytes preceded by its length as a varint
    */
-  bytes: () => number
+  bytes: () => Uint8Array
 
   /**
-   * Reads a string preceeded by its byte length as a varint
+   * Reads a string preceded by its byte length as a varint
    */
   string: () => string
 

packages/protons/src/index.ts

@@ -39,7 +39,6 @@ const encoderGenerators: Record<string, (val: string) => string> = {
   bool: (val) => `writer.bool(${val})`,
   bytes: (val) => `writer.bytes(${val})`,
   double: (val) => `writer.double(${val})`,
-  // enumeration: (val) => `writer.double(${val})`,
   fixed32: (val) => `writer.fixed32(${val})`,
   fixed64: (val) => `writer.fixed64(${val})`,
   float: (val) => `writer.float(${val})`,
@@ -58,7 +57,6 @@ const decoderGenerators: Record<string, () => string> = {
   bool: () => 'reader.bool()',
   bytes: () => 'reader.bytes()',
   double: () => 'reader.double()',
-  // enumeration: () => `writer.double(${val})`,
   fixed32: () => 'reader.fixed32()',
   fixed64: () => 'reader.fixed64()',
   float: () => 'reader.float()',
@@ -73,6 +71,24 @@ const decoderGenerators: Record<string, () => string> = {
   uint64: () => 'reader.uint64()'
 }
 
+const defaultValueGenerators: Record<string, () => string> = {
+  bool: () => 'false',
+  bytes: () => 'new Uint8Array(0)',
+  double: () => '0',
+  fixed32: () => '0',
+  fixed64: () => '0n',
+  float: () => '0',
+  int32: () => '0',
+  int64: () => '0n',
+  sfixed32: () => '0',
+  sfixed64: () => '0n',
+  sint32: () => '0',
+  sint64: () => '0n',
+  string: () => "''",
+  uint32: () => '0',
+  uint64: () => '0n'
+}
+
 function findTypeName (typeName: string, classDef: MessageDef, moduleDef: ModuleDef): string {
   if (types[typeName] != null) {
     return types[typeName]
@@ -117,6 +133,65 @@ function findDef (typeName: string, classDef: MessageDef, moduleDef: ModuleDef):
   throw new Error(`Could not resolve type name "${typeName}"`)
 }
 
+function createDefaultObject (fields: Record<string, FieldDef>, messageDef: MessageDef, moduleDef: ModuleDef): string {
+  const output = Object.entries(fields)
+    .map(([name, fieldDef]) => {
+      if (fieldDef.repeated) {
+        return `${name}: []`
+      }
+
+      if (fieldDef.optional) {
+        return ''
+      }
+
+      const type: string = fieldDef.type
+      let defaultValue
+
+      if (defaultValueGenerators[type] != null) {
+        defaultValue = defaultValueGenerators[type]()
+      } else {
+        const def = findDef(fieldDef.type, messageDef, moduleDef)
+
+        if (isEnumDef(def)) {
+          // select lowest-value enum - should be 0 but it's not guaranteed
+          const val = Object.entries(def.values)
+            .sort((a, b) => {
+              if (a[1] < b[1]) {
+                return 1
+              }
+
+              if (a[1] > b[1]) {
+                return -1
+              }
+
+              return 0
+            })
+            .pop()
+
+          if (val == null) {
+            throw new Error(`Could not find default enum value for ${def.fullName}`)
+          }
+
+          defaultValue = `${def.name}.${val[0]}`
+        } else {
+          defaultValue = 'undefined'
+        }
+      }
+
+      return `${name}: ${defaultValue}`
+    })
+    .filter(Boolean)
+    .join(',\n          ')
+
+  if (output !== '') {
+    return `
+          ${output}
+        `
+  }
+
+  return ''
+}
+
 const encoders: Record<string, string> = {
   bool: 'bool',
   bytes: 'bytes',
@@ -259,7 +334,7 @@ export interface ${messageDef.name} {
     const ensureArrayProps = Object.entries(fields)
       .map(([name, fieldDef]) => {
         // make sure repeated fields have an array if not set
-        if (fieldDef.rule === 'repeated') {
+        if (fieldDef.optional && fieldDef.rule === 'repeated') {
           return `        obj.${name} = obj.${name} ?? []`
         }
 
@@ -269,7 +344,7 @@ export interface ${messageDef.name} {
     const ensureRequiredFields = Object.entries(fields)
       .map(([name, fieldDef]) => {
         // make sure required fields are set
-        if (!fieldDef.optional) {
+        if (!fieldDef.optional && !fieldDef.repeated) {
           return `
         if (obj.${name} == null) {
           throw new Error('Protocol error: value for required field "${name}" was not found in protobuf')
@@ -331,7 +406,7 @@ ${Object.entries(fields)
           writer.ldelim()
         }
       }, (reader, length) => {
-        const obj: any = {}
+        const obj: any = {${createDefaultObject(fields, messageDef, moduleDef)}}
 
         const end = length == null ? reader.len : reader.pos + length
 
@@ -360,8 +435,10 @@ ${Object.entries(fields)
                 }
 
                 return `case ${fieldDef.id}:${fieldDef.rule === 'repeated'
+? `${fieldDef.optional
 ? `
-              obj.${name} = obj.${name} ?? []
+              obj.${name} = obj.${name} ?? []`
+: ''}
               obj.${name}.push(${decoderGenerators[type] == null ? `${codec}.decode(reader${type === 'message' ? ', reader.uint32()' : ''})` : decoderGenerators[type]()})`
 : `
               obj.${name} = ${decoderGenerators[type] == null ? `${codec}.decode(reader${type === 'message' ? ', reader.uint32()' : ''})` : decoderGenerators[type]()}`}

packages/protons/test/fixtures/basic.proto

@@ -2,5 +2,5 @@ syntax = "proto3";
 
 message Basic {
   optional string foo = 1;
-  required int32 num = 2;
+  int32 num = 2;
 }

packages/protons/test/fixtures/basic.ts

@@ -36,7 +36,9 @@ export namespace Basic {
           writer.ldelim()
         }
       }, (reader, length) => {
-        const obj: any = {}
+        const obj: any = {
+          num: 0
+        }
 
         const end = length == null ? reader.len : reader.pos + length
 

packages/protons/test/fixtures/circuit.ts

@@ -112,7 +112,10 @@ export namespace CircuitRelay {
             writer.ldelim()
           }
         }, (reader, length) => {
-          const obj: any = {}
+          const obj: any = {
+            id: new Uint8Array(0),
+            addrs: []
+          }
 
           const end = length == null ? reader.len : reader.pos + length
 
@@ -124,7 +127,6 @@ export namespace CircuitRelay {
                 obj.id = reader.bytes()
                 break
               case 2:
-                obj.addrs = obj.addrs ?? []
                 obj.addrs.push(reader.bytes())
                 break
               default:
@@ -133,16 +135,10 @@ export namespace CircuitRelay {
             }
           }
 
-          obj.addrs = obj.addrs ?? []
-
           if (obj.id == null) {
             throw new Error('Protocol error: value for required field "id" was not found in protobuf')
           }
 
-          if (obj.addrs == null) {
-            throw new Error('Protocol error: value for required field "addrs" was not found in protobuf')
-          }
-
           return obj
         })
       }