replace minixsv validator by lxml

lxml is available in standard distribution and is compatible with
python 2 and 3, which is not the case of minixsv

only constraint seems to be that complex regex patterns like negative
lookahead is not possible anymore, which is not a big deal since this
was not a valid XMLSchema format anyway

message_definitions/v1.0/pprz_schema.xsd

@@ -9,9 +9,9 @@
 <xs:attribute name="name"> <!-- msg_class, message,field -->
     <xs:simpleType>
         <xs:restriction base="xs:string">
-            <!-- class,long,var are currently used/valid field names in pprz -->
-            <xs:pattern value="^(?!break$|case$|catch$|const$|continue$|debugger$|default$|delete$|do$|else$|export$|extends$|finally$|for$|function$|if$|import$|in$|instanceof$|let$|new$|return$|super$|switch$|this$|throw$|try$|typeof$|void$|while$|with$|yield$|enum$|await$|implements$|package$|protected$|static$|interface$|private$|public$|abstract$|boolean$|byte$|char$|double$|final$|float$|goto$|int$|native$|short$|synchronized$|transient$|volatile$).+"/>
-            <!-- <xs:pattern value="^(?!break$|case$|class$|catch$|const$|continue$|debugger$|default$|delete$|do$|else$|export$|extends$|finally$|for$|function$|if$|import$|in$|instanceof$|let$|new$|return$|super$|switch$|this$|throw$|try$|typeof$|var$|void$|while$|with$|yield$|enum$|await$|implements$|package$|protected$|static$|interface$|private$|public$|abstract$|boolean$|byte$|char$|double$|final$|float$|goto$|int$|long$|native$|short$|synchronized$|transient$|volatile$).+"/> -->
+            <!-- for now, restrict to non-white characters -->
+            <xs:pattern value="[\S]+"/>
+            <!--xs:pattern value="^(?!break$|case$|catch$|const$|continue$|debugger$|default$|delete$|do$|else$|export$|extends$|finally$|for$|function$|if$|import$|in$|instanceof$|let$|new$|return$|super$|switch$|this$|throw$|try$|typeof$|void$|while$|with$|yield$|enum$|await$|implements$|package$|protected$|static$|interface$|private$|public$|abstract$|boolean$|byte$|char$|double$|final$|float$|goto$|int$|native$|short$|synchronized$|transient$|volatile$).+"/-->
         </xs:restriction>
     </xs:simpleType>
 </xs:attribute>

tools/generator/gen_messages.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 '''
 parse a PPRZ protocol XML file and generate appropriate implementation
@@ -39,22 +39,20 @@ def gen_messages(opts) :
     # Enable validation by default, disabling it if explicitly requested
     if opts.validate:
         try:
-            from lib.genxmlif import GenXmlIfError
-            from lib.minixsv import pyxsval
+            from lxml import etree
         except:
             print("WARNING: Unable to load XML validator libraries. XML validation will not be performed")
             opts.validate = False
 
     def pprz_validate(fname, schema, errorLimitNumber) :
         """Uses minixsv to validate an XML file with a given XSD schema file. We define pprz_validate
            here because it relies on the XML libs that were loaded in gen_messages(), so it can't be called standalone"""
-        # use default values of minixsv, location of the schema file must be specified in the XML file
         try:
-            domTreeWrapper = pyxsval.parseAndValidate(fname, xsdFile=schema, errorLimit=errorLimitNumber)
-        except pyxsval.XsvalError as errstr:
-            print(errstr)
-            return 1
-        except GenXmlIfError as errstr:
+            xmlschema_doc = etree.parse(schema)
+            xmlschema = etree.XMLSchema(xmlschema_doc)
+            f_doc = etree.parse(fname)
+            xmlschema.assertValid(f_doc)
+        except Exception as errstr:
             print(errstr)
             return 1
         return 0

tools/generator/gen_messages_v1_0_c.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 '''
 parse a PPRZLink protocol XML file and generate a C implementation
 

tools/generator/gen_messages_v2_0_c.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 '''
 parse a PPRZLink protocol XML file and generate a C implementation
 for version 2.0 of the protocol

tools/generator/gen_messages_v2_0_c_standalone.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 '''
 parse a PPRZLink protocol XML file and generate a C implementation
 for version 2.0 of the protocol