Schemas now support include files.

Bug: 15521443
Change-Id: I2e1ef97e7225a1a0ecf2ca65e31d49d443003747
Tested: on Linux.

docs/source/Grammar.md

@@ -1,6 +1,9 @@
 # Formal Grammar of the schema language
 
-schema = namespace\_decl | type\_decl | enum\_decl | root\_decl | object
+schema = include*
+         ( namespace\_decl | type\_decl | enum\_decl | root\_decl | object )*
+
+include = `include` string\_constant `;`
 
 namespace\_decl = `namespace` ident ( `.` ident )* `;`
 

docs/source/Schemas.md

@@ -141,6 +141,20 @@ These will generate the corresponding namespace in C++ for all helper
 code, and packages in Java. You can use `.` to specify nested namespaces /
 packages.
 
+### Includes
+
+You can include other schemas files in your current one, e.g.:
+
+    include "mydefinitions.fbs"
+    
+This makes it easier to refer to types defined elsewhere. `include`
+automatically ensures each file is parsed just once, even when referred to
+more than once.
+
+When using the `flatc` compiler to generate code for schema definitions,
+only definitions in the current file will be generated, not those from the
+included files (those you still generate separately).
+
 ### Root type
 
 This declares what you consider to be the root table (or struct) of the