feat(calc)): supports factorial

2 files changed, 4 insertions, 1 deletions

diff --git a/src/elixir_math_parser.yrl b/src/elixir_math_parser.yrl
index 86b36c8..0808683 100644
--- a/src/elixir_math_parser.yrl
+++ b/src/elixir_math_parser.yrl
@@ -10,7 +10,7 @@ Terminals
   int
   var
   break
-  '+' '-' '*' '/'
+  '+' '-' '*' '/' '!'
   '='
   '(' ')'
 .
@@ -24,6 +24,7 @@ Left 300 '+'.
 Left 300 '-'.
 Left 400 '*'.
 Left 400 '/'.
+Right 500 '!'.
 Left 600 '('.
 
 root -> statements : '$1'.
@@ -46,6 +47,7 @@ expr -> exprs '-' exprs : {sub_op, '$1', '$3'}.
 expr -> exprs '*' exprs : {mul_op, '$1', '$3'}.
 expr -> exprs '/' exprs : {div_op, '$1', '$3'}.
 expr -> '(' exprs ')' : '$2'.
+expr -> expr '!' : {factor_op, '$1'}.
 
 Erlang code.
 
diff --git a/src/elixir_math_parser_lexer.xrl b/src/elixir_math_parser_lexer.xrl
index facf323..5bdcbef 100644
--- a/src/elixir_math_parser_lexer.xrl
+++ b/src/elixir_math_parser_lexer.xrl
@@ -13,6 +13,7 @@ Rules.
 \=            : {token, {'=',  TokenLine}}.
 \(            : {token, {'(',  TokenLine}}.
 \)            : {token, {')',  TokenLine}}.
+!             : {token, {'!',  TokenLine}}.
 {BREAK}+      : {token, {break,  TokenLine}}.
 {NAME}        : {token, {var, TokenLine, TokenChars}}.
 {INT}         : {token, {int,  TokenLine, TokenChars}}.