A Very Ghetto JSON Writer

JsonBuilder.cs

public struct JsonBuilder
{
    private StringBuilder sb;
    public int Indentation;

    public JsonBuilder(StringBuilder sb)
    {
        Indentation = 0;
        this.sb = sb;
    }

    public void EndArray()
    {
        Indentation -= 4;
        BeforeEndOfItem('[');
        sb.Append(']');
    }

    public void EndObject()
    {
        Indentation -= 4;
        BeforeEndOfItem('{');
        sb.Append('}');
    }

    public void StartArray()
    {
        BeforeNextItem();
        sb.Append('[');
        Indentation += 4;
    }

    public void StartObject()
    {
        BeforeNextItem();
        sb.Append('{');
        Indentation += 4;
    }

    public void WriteName(string name)
    {
        BeforeNextItem();
        sb.Append('"').Append(name).Append("\": ");
    }

    public void WriteValue(bool value)
    {
        BeforeNextItem();
        sb.Append(value ? "true" : "false");
    }

    public void WriteValue(double value)
    {
        BeforeNextItem();
        sb.Append(value);
    }

    public void WriteValue(string value)
    {
        BeforeNextItem();
        if (value != null)
            sb.Append('"').Append(value).Append('"');
        else
            sb.Append("null");
    }

    private void BeforeEndOfItem(char startChar)
    {
        char end = sb[sb.Length - 1];
        if (end != startChar)
        {
            sb.Append("\n");
            for (int i = 0; i < Indentation; i++)
                sb.Append(' ');
        }
        else if (startChar == '{')
        {
            sb.Append(' ');
        }
    }

    private void BeforeNextItem()
    {
        char end = sb.Length > 0 ? sb[sb.Length - 1] : '\0';
        if (char.IsLetterOrDigit(end) || end == '"' || end == ']' || end == '}')
            sb.Append(",\n");
        else if (end == '[' || end == '{')
            sb.Append("\n");
        if (end != ' ')
            for (int i = 0; i < Indentation; i++)
                sb.Append(' ');
    }
}

For example,

var sb = new StringBuilder();
var json = new JsonBuilder(sb);
json.WriteName("OnPostprocessAllAssets");
json.StartObject();
json.WriteName("importedAssets");
json.StartArray();
foreach (var assetPath in importedAssets)
    json.WriteValue(assetPath);
json.EndArray();
json.WriteName("deletedAssets");
json.StartArray();
foreach (var assetPath in deletedAssets)
    json.WriteValue(assetPath);
json.EndArray();
json.WriteName("movedAssets");
json.StartArray();
foreach (var assetPath in movedAssets)
    json.WriteValue(assetPath);
json.EndArray();
json.WriteName("movedFromAssetPaths");
json.StartArray();
foreach (var assetPath in movedFromAssetPaths)
    json.WriteValue(assetPath);
json.EndArray();
json.EndObject();

will produce

"OnPostprocessAllAssets": {
    "importedAssets": [
        "Assets/Scripts/Editor/DebugProcessor.cs"
    ],
    "deletedAssets": [],
    "movedAssets": [],
    "movedFromAssetPaths": []
}