refactor: split point model and serialization

spec/flux/data_point_spec.cr

@@ -26,25 +26,4 @@ describe Flux::DataPoint do
       point.tags.should eq({:test => "bar"})
     end
   end
-
-  describe "#to_s" do
-    time = Time.now
-    ts = time.to_unix
-
-    it "serializes a simple point to line protocol" do
-      point = Flux::DataPoint.new "foo", time, a: 1
-      point.to_s.should eq("foo a=1 #{ts}")
-    end
-
-    it "serializes a multi-field point to line protocol" do
-      point = Flux::DataPoint.new "foo", time, a: 1, b: true
-      point.to_s.should eq("foo a=1,b=t #{ts}")
-    end
-
-    it "serializes when tags are present" do
-      point = Flux::DataPoint.new "foo", time, a: 1
-      point.tag :test, "bar"
-      point.to_s.should eq("foo,test=bar a=1 #{ts}")
-    end
-  end
 end

spec/flux/line_protocol_spec.cr

@@ -0,0 +1,24 @@
+require "../spec_helper"
+
+describe Flux::LineProtocol do
+  describe ".serialize" do
+    time = Time.now
+    ts = time.to_unix
+
+    it "serializes a simple point to line protocol" do
+      point = Flux::DataPoint.new "foo", time, a: 1
+      Flux::LineProtocol.serialize(point).should eq("foo a=1 #{ts}")
+    end
+
+    it "serializes a multi-field point to line protocol" do
+      point = Flux::DataPoint.new "foo", time, a: 1, b: true
+      Flux::LineProtocol.serialize(point).should eq("foo a=1,b=t #{ts}")
+    end
+
+    it "serializes when tags are present" do
+      point = Flux::DataPoint.new "foo", time, a: 1
+      point.tag :test, "bar"
+      Flux::LineProtocol.serialize(point).should eq("foo,test=bar a=1 #{ts}")
+    end
+  end
+end

src/flux/data_point.cr

@@ -1,4 +1,4 @@
-# Model and serialization tools for InfluxDB data points.
+# Model for InfluxDB data points.
 struct Flux::DataPoint
   alias TagSet = Hash(Symbol, String | Symbol)
 
@@ -28,41 +28,8 @@ struct Flux::DataPoint
     tags[key] = value
   end
 
-  # Serializes the point to InfluxDB line protocol.
-  # See https://v2.docs.influxdata.com/v2.0/reference/syntax/line-protocol/
-  def to_s(io : IO)
-    io << @measurement
-
-    @tags.try(
-      &.each do |k, v|
-        io << ','
-        io << k
-        io << '='
-        io << v
-      end
-    )
-
-    io << ' '
-
-    fields.join(',', io) do |(k, v), field|
-      field << k
-      field << '='
-      case v
-      when String
-        field << '"'
-        field << v
-        field << '"'
-      when true
-        field << 't'
-      when false
-        field << 'f'
-      else
-        field << v
-      end
-    end
-
-    io << ' '
-
-    io << timestamp.to_unix
+  # Checks if any tags are defined for the point.
+  def tagged?
+    !@tags.nil?
   end
 end

src/flux/line_protocol.cr

@@ -0,0 +1,50 @@
+require "./data_point"
+
+# Tools for InfluxDB line protocol marshalling.
+# See https://v2.docs.influxdata.com/v2.0/reference/syntax/line-protocol/
+# TODO: escape special chars
+module Flux::LineProtocol
+  # Appends *point* onto *io* in line protocol format.
+  def self.serialize(point : DataPoint, io : IO) : Nil
+    io << point.measurement
+
+    if point.tagged?
+      point.tags.each do |k, v|
+        io << ','
+        io << k
+        io << '='
+        io << v
+      end
+    end
+
+    io << ' '
+
+    point.fields.join(',', io) do |(k, v), field|
+      field << k
+      field << '='
+      case v
+      when String
+        field << '"'
+        field << v
+        field << '"'
+      when true
+        field << 't'
+      when false
+        field << 'f'
+      else
+        field << v
+      end
+    end
+
+    io << ' '
+
+    io << point.timestamp.to_unix
+  end
+
+  # Serializes *point* to a line protocol row.
+  def self.serialize(point : DataPoint) : String
+    String.build do |io|
+      serialize point, io
+    end
+  end
+end