leex_in_action.adoc

Leex 实战 — 单词统计应用

词法文件

wc.xrl

Definitions.

Char = [a-zA-Z]
EOL = \n

Rules.

{Char}+ :
  {token, {word, TokenLen}}.
{EOL} :
  {token, {line, 1}}.
. :
  {token, {char, 1}}.

Erlang code.

-export([count/1]).

count(String) ->
  {ok, Tokens, _} = string(String),
  LineCount = lists:sum([element(2, T) || T <- Tokens, element(1, T) == line]),
  WordCount = lists:sum([1 || T <- Tokens, element(1, T) == word]),
  CharCount = lists:sum([element(2, T) || T <- Tokens]),
  io:format("Lines: ~p Words: ~p Chars: ~p~n", [LineCount, WordCount, CharCount]).

构建

Makefile

Q := @

WC := wc.erl

default: shell

$(WC): wc.xrl
	$(Q) mkdir -p ebin
	$(Q) erlc -o $@ +'{verbose,true}' +'{report,true}' $<
	$(Q) erlc -o ebin $(WC)

shell: clean $(WC)
	erl -pa ebin

clean:
	$(Q) rm -fr ebin $(WC)

执行

$ make shell
> wc:count("hello, leex!\n").