Add basic grammar and Makefile.

Makefile

@@ -0,0 +1,12 @@
+.PHONY: test clean
+
+PERParser.py :
+	antlr4 -Dlanguage=Python3 PER.g4
+
+test : export CLASSPATH = /usr/share/java/stringtemplate4.jar:/usr/share/java/antlr4.jar:/usr/share/java/antlr4-runtime.jar:/usr/share/java/antlr3-runtime.jar/:/usr/share/java/treelayout.jar
+test :
+	antlr4 PER.g4 && javac *.java
+	grun PER per testinput -tokens
+
+clean :
+	rm -f *.java *.class PERParser.py PERLexer.py PERListener.py *.interp *.tokens

PER.g4

@@ -0,0 +1,40 @@
+grammar PER;
+
+/*
+ * Parser
+ */
+
+per                 : (statement | comment | WHITESPACE)+ EOF ;
+statement           : OPEN command CLOSE ;
+comment             : COMMENT ;
+command             : ( defrule | defconst ) ;
+defrule             : DEFRULE WHITESPACE+ proposition_list DEFRULE_SEPARATOR WHITESPACE* action_list ;
+proposition_list    : ( proposition WHITESPACE+ )+ ;
+proposition         : OPEN SYMBOL ( WHITESPACE (REL_OP | SYMBOL | SHORT) )+ WHITESPACE? CLOSE ;
+action_list         : ( action WHITESPACE+ )+ ;
+action              : OPEN SYMBOL ( WHITESPACE (SYMBOL | SHORT | STRING) )+ WHITESPACE? CLOSE ;
+defconst            : DEFCONST WHITESPACE+ SYMBOL WHITESPACE+ SHORT ;
+
+/*
+ * Lexer
+ */
+
+OPEN                : '(' ;
+CLOSE               : ')' ;
+WHITESPACE          : ( ' ' | '\t' | NEWLINE ) ;
+NEWLINE             : ( '\n' | '\r\n' ) ;
+
+COMMENT             : ';' ~[\r\n]* NEWLINE ;
+
+DEFRULE             : 'defrule' ;
+DEFRULE_SEPARATOR   : '=>' ;
+
+REL_OP              : ( REL_OP_FULL | REL_OP_SHORT ) ;
+REL_OP_FULL         : ( 'less-than' | 'less-or-equal' | 'greater-than' | 'greater-or-equal' | 'equal' | 'not-equal' ) ;
+REL_OP_SHORT        : ( '<' | '<=' | '>' | '>=' | '==' | '!=' ) ;
+
+DEFCONST            : 'defconst' ;
+
+STRING              : '"' ~["]* '"' ;
+SHORT               : '-'? [0-9]+ ; // This needs to go at the bottom to make it lowere precedence than FACT_ARG... but that probably breaks defconst... FIXME
+SYMBOL              : [a-z0-9\-]+ ; // This is likely too restrictive, but covers all of the values actually defined in the TC guide

Pipfile

@@ -0,0 +1,12 @@
+[[source]]
+name = "pypi"
+url = "https://pypi.org/simple"
+verify_ssl = true
+
+[dev-packages]
+
+[packages]
+antlr4-python3-runtime = "*"
+
+[requires]
+python_version = "3.6"

testinput

@@ -0,0 +1,8 @@
+(defrule
+    (player-in-game 1)
+    (player-human 1)
+    (goal 1 1)
+    =>
+    (chat-to-player 1 "3 Train villagers, build 2 houses, and send 6 to sheep [7 pop](6 sheep)")
+    (set-goal 1 2)
+)