From 9c87737c9abefdf059a06f1213e8dee2d87f308a Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Wed, 9 Apr 2014 11:58:44 -0700
Subject: adding a bind value collector

---
 lib/arel/collectors/bind.rb            | 32 ++++++++++++++++++
 lib/arel/collectors/sql_string.rb      |  5 +--
 lib/arel/visitors/to_sql.rb            |  5 ++-
 test/collectors/test_bind_collector.rb | 62 ++++++++++++++++++++++++++++++++++
 4 files changed, 99 insertions(+), 5 deletions(-)
 create mode 100644 lib/arel/collectors/bind.rb
 create mode 100644 test/collectors/test_bind_collector.rb

diff --git a/lib/arel/collectors/bind.rb b/lib/arel/collectors/bind.rb
new file mode 100644
index 0000000000..4309de75c9
--- /dev/null
+++ b/lib/arel/collectors/bind.rb
@@ -0,0 +1,32 @@
+module Arel
+  module Collectors
+    class Bind
+      def initialize
+        @parts = []
+      end
+
+      def << str
+        @parts << str
+        self
+      end
+
+      def add_bind bind
+        @parts << bind
+        self
+      end
+
+      def value; @parts; end
+
+      def substitute_binds bvs
+        bvs = bvs.dup
+        @parts.map do |val|
+          if Arel::Nodes::BindParam === val
+            bvs.shift
+          else
+            val
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/arel/collectors/sql_string.rb b/lib/arel/collectors/sql_string.rb
index 824b0a1712..526de66416 100644
--- a/lib/arel/collectors/sql_string.rb
+++ b/lib/arel/collectors/sql_string.rb
@@ -16,11 +16,8 @@ module Arel
         self
       end
 
-      def start;  self; end
-      def finish; self; end
-
       def add_bind bind
-        self << bind
+        self << bind.to_s
         self
       end
     end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index fd1332a4db..9cda88454b 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -693,7 +693,10 @@ module Arel
 
       def literal o, collector; collector << o.to_s; end
 
-      alias :visit_Arel_Nodes_BindParam  :literal
+      def visit_Arel_Nodes_BindParam o, collector
+        collector.add_bind o
+      end
+
       alias :visit_Arel_Nodes_SqlLiteral :literal
       alias :visit_Bignum                :literal
       alias :visit_Fixnum                :literal
diff --git a/test/collectors/test_bind_collector.rb b/test/collectors/test_bind_collector.rb
new file mode 100644
index 0000000000..c7748d7d10
--- /dev/null
+++ b/test/collectors/test_bind_collector.rb
@@ -0,0 +1,62 @@
+require 'helper'
+require 'arel/collectors/bind'
+
+module Arel
+  module Collectors
+    class TestBindCollector < Arel::Test
+      def setup
+        @conn = FakeRecord::Base.new
+        @visitor = Visitors::ToSql.new @conn.connection
+        super
+      end
+
+      def collect node
+        @visitor.accept(node, Collectors::Bind.new)
+      end
+
+      def compile node
+        collect(node).value
+      end
+
+      def ast_with_binds bv
+        table = Table.new(:users)
+        manager = Arel::SelectManager.new Table.engine, table
+        manager.where(table[:age].eq(bv))
+        manager.where(table[:name].eq(bv))
+        manager.ast
+      end
+
+      def test_leaves_binds
+        node = Nodes::BindParam.new 'omg'
+        list = compile node
+        assert_equal node, list.first
+        assert_equal node.class, list.first.class
+      end
+
+      def test_adds_strings
+        bv = Nodes::BindParam.new('?')
+        list = compile ast_with_binds bv
+        assert_operator list.length, :>, 0
+        assert_equal bv, list.grep(Nodes::BindParam).first
+        assert_equal bv.class, list.grep(Nodes::BindParam).first.class
+      end
+
+      def test_substitute_binds
+        bv = Nodes::BindParam.new('?')
+        collector = collect ast_with_binds bv
+
+        values = collector.value
+
+        offsets = values.map.with_index { |v,i|
+          [v,i]
+        }.find_all { |(v,i)| Nodes::BindParam === v }.map(&:last)
+
+        list = collector.substitute_binds ["hello", "world"]
+        assert_equal "hello", list[offsets[0]]
+        assert_equal "world", list[offsets[1]]
+
+        assert_equal 'SELECT FROM "users" WHERE "users"."age" = hello AND "users"."name" = world', list.join
+      end
+    end
+  end
+end
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