Function ragel FSM is not used

[abargnesi]

The function ragel FSM is not used anywhere.

Additionally it defines term as alpha+ excluding underscore. This is at odds with parsing terms.

$ rlwrap ruby -I lib lib/bel_parser/parsers/common/function.rb
protein_abundance
s(:function,
  s(:identifier, "protein_"))

$ rlwrap ruby -I lib lib/bel_parser/parsers/expression/term.rb
protein_abundance(HGNC:AKT1)
s(:term,
  s(:function,
    s(:identifier, "protein_abundance")),
  s(:argument,
    s(:parameter,
      s(:prefix,
        s(:identifier, "HGNC")),
      s(:value,
        s(:identifier, "AKT1")))))

Should we update the definition in common/function.rl or just remove it?

/cc @nbargnesi

[nbargnesi]

It was being used in the rewritten term machines at one point. It made those term machines much easier to follow. If it still has a place there, we can keep it. If not, drop it.

[abargnesi]

I agree that a specific parse type makes it easier to follow. We should keep the definition and reuse it in term. However, we should change the common.rl FUNCTION definition from the build-in machine alpha+ to something more liberal.

[abargnesi]

Redefined function to a specific ASCII range (excluding parenthesis chars), but compiling statement machines hangs. The compilation consistently consumes memory and never completes.

Diff:

diff --git a/lib/bel_parser/parsers/common/common.rl b/lib/bel_parser/parsers/common/common.rl
index de2f49b..54dd305 100644
--- a/lib/bel_parser/parsers/common/common.rl
+++ b/lib/bel_parser/parsers/common/common.rl
@@ -7,16 +7,16 @@ machine bel;
   WS          = space;
   EQL         = '=';
   NUMBER_SIGN = '#';
-  SQ             = "'";
+  SQ          = "'";
   DQ          = '"';
   COLON       = ':';
   ESCAPED     = /\\./;
-  NOT_SQESC      = [^'\\];
-  NOT_DQESC      = [^"\\];
+  NOT_SQESC   = [^'\\];
+  NOT_DQESC   = [^"\\];
   COMMA_DELIM = SP* ',' SP*;
   SS          = '//';
-  ID_CHARS   = [a-zA-Z0-9_]+;
-  LP         = '(';
+  ID_CHARS    = [a-zA-Z0-9_]+;
+  LP          = '(';
   RP          = ')';

   KW_SET = /SET/i;
@@ -63,9 +63,10 @@ machine bel;
     alpha+
     ;

-   FUNCTION =
-       alpha+
-       ;
+  # Excludes 0x28 (open parenthesis) and 0x29 (close parenthesis).
+  FUNCTION =
+    (0x21..0x27 | 0x2a..0x7e)+
+    ;
 }%%
 =end
 # vim: ts=2 sw=2 ft=ragel:
diff --git a/lib/bel_parser/parsers/expression/term.rl b/lib/bel_parser/parsers/expression/term.rl
index ac28863..f89cd69 100644
--- a/lib/bel_parser/parsers/expression/term.rl
+++ b/lib/bel_parser/parsers/expression/term.rl
@@ -3,23 +3,9 @@
 %%{
   machine bel;

+  include 'function.rl';
   include 'parameter.rl';

-  action start_function {
-    $stderr.puts 'TERM start_function'
-    @buffers[:function] = []
-  }
-
-  action append_function {
-    $stderr.puts 'TERM append_function'
-    @buffers[:function] << fc
-  }
-
-  action finish_function {
-    $stderr.puts 'TERM finish_function'
-    @buffers[:function] = identifier(utf8_string(@buffers[:function]))
-  }
-
   action term_init {
     $stderr.puts 'TERM term_init'
     @buffers[:term_stack] = [ term() ]
@@ -32,9 +18,7 @@

   action term_fx {
     $stderr.puts 'TERM term_fx'
-    fx = @buffers[:function]
-    fx_node = function(fx)
-    new_term = @buffers[:term_stack][-1] << fx_node
+    new_term = @buffers[:term_stack][-1] << @buffers[:function]
     @buffers[:term_stack][-1] = new_term
   }

@@ -48,7 +32,8 @@

   action fxbt {
     $stderr.puts 'TERM fxbt'
-    fpc -= @buffers[:function].length + 1
+    function_string = @buffers[:function].identifier.string_literal
+    fpc -= function_string.length + 1
     fcall inner_term;
   }

@@ -78,35 +63,35 @@
   }

   inner_term :=
-    an_ident >inner_term_init >start_function $append_function %finish_function
+    a_function >inner_term_init
     SP*
     '(' @term_fx $eof{ $stderr.puts "EOF!" }
       (
         a_parameter %term_argument |
-        an_ident >start_function $append_function '(' @fxbt
+        a_function '(' @fxbt
       )
       (
         COMMA_DELIM
         (
           a_parameter %term_argument |
-          an_ident >start_function $append_function '(' @fxbt
+          a_function '(' @fxbt
         )
       )*
     ')' @fxret;

   outer_term =
-    an_ident >term_init >start_function $append_function %finish_function
+    a_function >term_init
     SP*
     '(' @term_fx
       (
         a_parameter %term_argument $eof(eof_parameter_argument) |
-        an_ident >start_function $append_function '(' @fxbt
+        a_function '(' @fxbt
       )
       (
         COMMA_DELIM
         (
           a_parameter %term_argument $eof(eof_parameter_argument) |
-          an_ident >start_function $append_function '(' @fxbt
+          a_function '(' @fxbt
         )
       )*
     ')';