From be1fa03e5782657a9503bf0c9350b265048fe5d5 Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@fri.uni-lj.si>
Date: Sun, 24 Apr 2016 22:42:30 +0200
Subject: Support CLP(R) expressions in Prolog parser

---
 prolog/lexer.py  |  1 +
 prolog/parser.py | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/prolog/lexer.py b/prolog/lexer.py
index 799ebb9..7ca67e1 100644
--- a/prolog/lexer.py
+++ b/prolog/lexer.py
@@ -53,6 +53,7 @@ operators = {
     r'//':  'IDIV',
     r'mod': 'MOD',
     r'**':  'POW',
+    r'^':   'POW',
     r'.':   'PERIOD',
     r',':   'COMMA',
     r';':   'SEMI'
diff --git a/prolog/parser.py b/prolog/parser.py
index 0c539d5..19d2da5 100644
--- a/prolog/parser.py
+++ b/prolog/parser.py
@@ -151,6 +151,10 @@ def p_term_simple(p):
             | VARIABLE'''
     p[0] = Tree('term', [make_token(p, 1)])
 
+def p_term_clpr(p):
+    'term : LBRACE clpr RBRACE'
+    p[0] = Tree('term', [make_token(p, 1), p[2], make_token(p, 3)])
+
 def p_args_single(p):
     'args : term'
     p[0] = Tree('args', [p[1]])
@@ -174,6 +178,46 @@ def p_functor(p):
     'functor : NAME'
     p[0] = Tree('functor', [make_token(p, 1)])
 
+# CLP(R) syntax
+def p_clpr_single(p):
+    'clpr : clpr_constr'
+    p[0] = Tree('clpr', [p[1]])
+def p_clpr_more(p):
+    '''clpr : clpr_constr COMMA clpr
+            | clpr_constr SEMI clpr'''
+    p[0] = Tree('clpr', [p[1], make_token(p, 2), p[3]])
+
+def p_clpr_constr(p):
+    '''clpr_constr : clpr_expr LT clpr_expr
+                   | clpr_expr GT clpr_expr
+                   | clpr_expr LE clpr_expr
+                   | clpr_expr GE clpr_expr
+                   | clpr_expr NEQA clpr_expr
+                   | clpr_expr EQA clpr_expr
+                   | clpr_expr EQU clpr_expr'''
+    p[0] = Tree('clpr_constr', [p[1], make_token(p, 2), p[3]])
+
+def p_clpr_expr_value(p):
+    '''clpr_expr : VARIABLE
+                 | UINTEGER
+                 | UREAL'''
+    p[0] = Tree('clpr_expr', [make_token(p, 1)])
+def p_clpr_expr_unary(p):
+    '''clpr_expr : MINUS clpr_expr %prec UMINUS
+                 | PLUS clpr_expr %prec UPLUS'''
+    p[0] = Tree('clpr_expr', [make_token(p, 1), p[2]])
+def p_clpr_expr_binary(p):
+    '''clpr_expr : clpr_expr PLUS clpr_expr
+                 | clpr_expr MINUS clpr_expr
+                 | clpr_expr STAR clpr_expr
+                 | clpr_expr DIV clpr_expr
+                 | clpr_expr POW clpr_expr
+                 | clpr_expr NAME clpr_expr'''  # XXX a hack to allow (X)*(X) without spaces
+    p[0] = Tree('clpr_expr', [p[1], make_token(p, 2), p[3]])
+def p_clpr_expr_parens(p):
+    'clpr_expr : LPAREN clpr_expr RPAREN'
+    p[0] = Tree('clpr_expr', [make_token(p, 1), p[2], make_token(p, 3)])
+
 def p_error(t):
     if t is None:
         raise SyntaxError('unexpected end of file')
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