Address Mike's feedback: move sys prop eval higher.

In this commit, I've removed the `PrecedenceChecks#Configuration` class
in favour of a static method within `TargetCodeGeneratorLoader`.

Unfortunately, C# behaves differently to all the other code generators.
To avoid duplicating the default configuration for precedence checks in
the `CSharp` class, I've made the method publicly visible, which is a
bit ugly.

It has also introduced a cyclic dependency between the code generators,
e.g., `JavaGenerator`, and `TargetCodeGeneratorLoader`, as in order to
preserve the existing public signatures I have kept the old constructors
around and supplied a default `PrecedenceChecks`.

Author: ZachBray

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/TargetCodeGeneratorLoader.java

@@ -54,7 +54,7 @@ public CodeGenerator newInstance(final Ir ir, final String outputDir)
                 "true".equals(System.getProperty(JAVA_GENERATE_INTERFACES)),
                 "true".equals(System.getProperty(DECODE_UNKNOWN_ENUM_VALUES)),
                 "true".equals(System.getProperty(TYPES_PACKAGE_OVERRIDE)),
-                PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+                precedenceChecks(),
                 new JavaOutputManager(outputDir, ir.applicableNamespace()));
         }
     },
@@ -86,7 +86,7 @@ public CodeGenerator newInstance(final Ir ir, final String outputDir)
             return new CppGenerator(
                 ir,
                 "true".equals(System.getProperty(DECODE_UNKNOWN_ENUM_VALUES)),
-                PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+                precedenceChecks(),
                 new NamespaceOutputManager(outputDir, ir.applicableNamespace()));
         }
     },
@@ -121,6 +121,30 @@ public CodeGenerator newInstance(final Ir ir, final String outputDir)
         }
     };
 
+    /**
+     * Returns the configured precedence checks.
+     *
+     * @return the configured precedence checks.
+     */
+    public static PrecedenceChecks precedenceChecks()
+    {
+        final boolean shouldGeneratePrecedenceChecks =
+            Boolean.parseBoolean(System.getProperty(GENERATE_PRECEDENCE_CHECKS, "false"));
+
+        final String precedenceChecksFlagName =
+            System.getProperty(PRECEDENCE_CHECKS_FLAG_NAME, "SBE_ENABLE_PRECEDENCE_CHECKS");
+
+        final String precedenceChecksPropName =
+            System.getProperty(JAVA_PRECEDENCE_CHECKS_PROPERTY_NAME, "sbe.enable.precedence.checks");
+
+        final PrecedenceChecks.Context context = new PrecedenceChecks.Context()
+            .shouldGeneratePrecedenceChecks(shouldGeneratePrecedenceChecks)
+            .precedenceChecksFlagName(precedenceChecksFlagName)
+            .precedenceChecksPropName(precedenceChecksPropName);
+
+        return PrecedenceChecks.newInstance(context);
+    }
+
     /**
      * Do a case-insensitive lookup of a target language for code generation.
      *

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/common/PrecedenceChecks.java

@@ -15,7 +15,6 @@
  */
 package uk.co.real_logic.sbe.generation.common;
 
-import uk.co.real_logic.sbe.SbeTool;
 import uk.co.real_logic.sbe.ir.Token;
 
 import java.util.ArrayList;
@@ -161,45 +160,14 @@ private FieldPrecedenceModel createModel(
         return null;
     }
 
-    static final class Configuration
-    {
-        private static final boolean GENERATE_PRECEDENCE_CHECKS_VALUE =
-            Boolean.parseBoolean(System.getProperty(SbeTool.GENERATE_PRECEDENCE_CHECKS, "false"));
-
-        private static final String PRECEDENCE_CHECKS_FLAG_NAME_VALUE =
-            System.getProperty(SbeTool.PRECEDENCE_CHECKS_FLAG_NAME, "SBE_ENABLE_PRECEDENCE_CHECKS");
-
-        private static final String PRECEDENCE_CHECKS_PROPERTY_NAME_VALUE =
-            System.getProperty(SbeTool.JAVA_PRECEDENCE_CHECKS_PROPERTY_NAME, "sbe.enable.precedence.checks");
-
-        private Configuration()
-        {
-        }
-
-        static boolean shouldGeneratePrecedenceChecks()
-        {
-            return GENERATE_PRECEDENCE_CHECKS_VALUE;
-        }
-
-        static String precedenceChecksFlagName()
-        {
-            return PRECEDENCE_CHECKS_FLAG_NAME_VALUE;
-        }
-
-        static String precedenceChecksPropName()
-        {
-            return PRECEDENCE_CHECKS_PROPERTY_NAME_VALUE;
-        }
-    }
-
     /**
      * The context describing how precedence checks should be generated.
      */
     public static final class Context
     {
-        private boolean shouldGeneratePrecedenceChecks = Configuration.shouldGeneratePrecedenceChecks();
-        private String precedenceChecksFlagName = Configuration.precedenceChecksFlagName();
-        private String precedenceChecksPropName = Configuration.precedenceChecksPropName();
+        private boolean shouldGeneratePrecedenceChecks;
+        private String precedenceChecksFlagName;
+        private String precedenceChecksPropName;
 
         /**
          * Returns {@code true} if precedence checks should be generated; {@code false} otherwise.

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java

@@ -18,6 +18,7 @@
 import uk.co.real_logic.sbe.PrimitiveType;
 import uk.co.real_logic.sbe.generation.CodeGenerator;
 import uk.co.real_logic.sbe.generation.Generators;
+import uk.co.real_logic.sbe.generation.TargetCodeGeneratorLoader;
 import uk.co.real_logic.sbe.generation.common.FieldPrecedenceModel;
 import uk.co.real_logic.sbe.generation.common.PrecedenceChecks;
 import uk.co.real_logic.sbe.ir.Encoding;
@@ -71,7 +72,7 @@ public CppGenerator(final Ir ir, final boolean shouldDecodeUnknownEnumValues, fi
         this(
             ir,
             shouldDecodeUnknownEnumValues,
-            PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+            TargetCodeGeneratorLoader.precedenceChecks(),
             outputManager
         );
     }

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/csharp/CSharp.java

@@ -18,7 +18,7 @@
 
 import uk.co.real_logic.sbe.generation.CodeGenerator;
 import uk.co.real_logic.sbe.generation.TargetCodeGenerator;
-import uk.co.real_logic.sbe.generation.common.PrecedenceChecks;
+import uk.co.real_logic.sbe.generation.TargetCodeGeneratorLoader;
 import uk.co.real_logic.sbe.ir.Ir;
 
 /**
@@ -33,7 +33,7 @@ public CodeGenerator newInstance(final Ir ir, final String outputDir)
     {
         return new CSharpGenerator(
             ir,
-            PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+            TargetCodeGeneratorLoader.precedenceChecks(),
             new CSharpNamespaceOutputManager(outputDir, ir.applicableNamespace()));
     }
 }

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/csharp/CSharpGenerator.java

@@ -20,6 +20,7 @@
 import uk.co.real_logic.sbe.PrimitiveValue;
 import uk.co.real_logic.sbe.generation.CodeGenerator;
 import uk.co.real_logic.sbe.generation.Generators;
+import uk.co.real_logic.sbe.generation.TargetCodeGeneratorLoader;
 import uk.co.real_logic.sbe.generation.common.FieldPrecedenceModel;
 import uk.co.real_logic.sbe.generation.common.PrecedenceChecks;
 import uk.co.real_logic.sbe.ir.Encoding;
@@ -71,7 +72,7 @@ public CSharpGenerator(final Ir ir, final OutputManager outputManager)
     {
         this(
             ir,
-            PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+            TargetCodeGeneratorLoader.precedenceChecks(),
             outputManager
         );
     }

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaGenerator.java

@@ -18,6 +18,7 @@
 import uk.co.real_logic.sbe.PrimitiveType;
 import uk.co.real_logic.sbe.generation.CodeGenerator;
 import uk.co.real_logic.sbe.generation.Generators;
+import uk.co.real_logic.sbe.generation.TargetCodeGeneratorLoader;
 import uk.co.real_logic.sbe.generation.common.FieldPrecedenceModel;
 import uk.co.real_logic.sbe.generation.common.PrecedenceChecks;
 import uk.co.real_logic.sbe.ir.*;
@@ -130,7 +131,7 @@ public JavaGenerator(
             shouldGenerateInterfaces,
             shouldDecodeUnknownEnumValues,
             shouldSupportTypesPackageNames,
-            PrecedenceChecks.newInstance(new PrecedenceChecks.Context()),
+            TargetCodeGeneratorLoader.precedenceChecks(),
             outputManager
         );
     }

sbe-tool/src/test/java/uk/co/real_logic/sbe/generation/java/JavaGeneratorTest.java

@@ -260,7 +260,10 @@ void shouldGenerateBasicMessage() throws Exception
     @Test
     void shouldGenerateWithoutPrecedenceChecksByDefault() throws Exception
     {
-        final PrecedenceChecks.Context context = new PrecedenceChecks.Context();
+        final PrecedenceChecks.Context context = new PrecedenceChecks.Context()
+            .shouldGeneratePrecedenceChecks(false)
+            .precedenceChecksPropName("sbe.enable.precedence.checks")
+            .precedenceChecksFlagName("SBE_ENABLE_PRECEDENCE_CHECKS");
         final PrecedenceChecks precedenceChecks = PrecedenceChecks.newInstance(context);
         generator(precedenceChecks).generate();
 
@@ -276,7 +279,9 @@ void shouldGenerateWithoutPrecedenceChecksByDefault() throws Exception
     void shouldGeneratePrecedenceChecksWhenEnabled() throws Exception
     {
         final PrecedenceChecks.Context context = new PrecedenceChecks.Context()
-            .shouldGeneratePrecedenceChecks(true);
+            .shouldGeneratePrecedenceChecks(true)
+            .precedenceChecksPropName("sbe.enable.precedence.checks")
+            .precedenceChecksFlagName("SBE_ENABLE_PRECEDENCE_CHECKS");
         final PrecedenceChecks precedenceChecks = PrecedenceChecks.newInstance(context);
         generator(precedenceChecks).generate();