From 75a92efe9ee1f9b0d7ca34f9f81af25e7921020e Mon Sep 17 00:00:00 2001
From: Derek Perez <derek@perez.earth>
Date: Sun, 4 Aug 2019 18:46:18 -0700
Subject: [PATCH] introduces FieldType.inferFrom and a simplified
 OptionSpec.Builder.setValue which makes use of it.

---
 java/protopoet/FieldType.java  | 51 ++++++++++++++++++++++++++++------
 java/protopoet/OptionSpec.java | 10 +++++++
 2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/java/protopoet/FieldType.java b/java/protopoet/FieldType.java
index 24d9801..2d56144 100644
--- a/java/protopoet/FieldType.java
+++ b/java/protopoet/FieldType.java
@@ -16,9 +16,9 @@
 
 package protopoet;
 
-/** 
- * All standard scalar types a field may represent.
- * Learn more: https://developers.google.com/protocol-buffers/docs/reference/proto3-spec#fields
+/**
+ * All standard scalar types a field may represent. Learn more:
+ * https://developers.google.com/protocol-buffers/docs/reference/proto3-spec#fields
  */
 public enum FieldType {
   DOUBLE,
@@ -39,6 +39,41 @@ public enum FieldType {
   MESSAGE,
   ENUM;
 
+  /**
+   * Attempts to guess at the FieldType based on the provided value. Note, this outputs INT32
+   * forInteger and INT64 for Long, if you need more specific types for numerics, don't use this.
+   */
+  public static FieldType inferFrom(Object value) {
+    if (value instanceof Double) {
+      return DOUBLE;
+    }
+    if (value instanceof Float) {
+      return FLOAT;
+    }
+    if (value instanceof Integer) {
+      return INT32;
+    }
+    if (value instanceof Long) {
+      return INT64;
+    }
+    if (value instanceof Boolean) {
+      return BOOL;
+    }
+    if (value instanceof String) {
+      return STRING;
+    }
+    if (value instanceof byte[]) {
+      return BYTES;
+    }
+    if (value instanceof Enum) {
+      return ENUM;
+    }
+    if (value instanceof Object) {
+      return MESSAGE;
+    }
+    throw new IllegalArgumentException("unable to express FieldType for value");
+  }
+
   @Override
   public String toString() {
     return name().toLowerCase();
@@ -46,11 +81,11 @@ public String toString() {
 
   String formatValue(Object value) {
     switch (this) {
-    case STRING:
-    case BYTES:
-      return String.format("\"%s\"", value);
-    default:
-      return value.toString();
+      case STRING:
+      case BYTES:
+        return String.format("\"%s\"", value);
+      default:
+        return value.toString();
     }
   }
 }
diff --git a/java/protopoet/OptionSpec.java b/java/protopoet/OptionSpec.java
index 4c2bff8..675248d 100644
--- a/java/protopoet/OptionSpec.java
+++ b/java/protopoet/OptionSpec.java
@@ -252,6 +252,16 @@ public Builder setOptionComment(String... lines) {
       return setOptionComment(ImmutableList.copyOf(lines));
     }
 
+    /**
+     * Sets value and infers the field type based on passed in value. Check {@link FieldType} for
+     * more info on how it does it, if you need more granularity or predictibility, don't use this.
+     */
+    public Builder setValue(Object value) {
+      optionValueType = FieldType.inferFrom(value);
+      optionValue = value;
+      return this;
+    }
+
     /** Sets an integer-based value (eg: int32, uint32, fixed32, sfixed32). */
     public Builder setValue(FieldType valueType, int intValue) {
       switch (valueType) {