core: add calculation of expression in evaluation of expressions with "calc:..." (issue #997)

3 files changed, 24 insertions, 4 deletions

diff --git a/doc/en/autogen/user/weechat_commands.adoc b/doc/en/autogen/user/weechat_commands.adoc
index 89aad68d6..2cf3cf4c1 100644
--- a/doc/en/autogen/user/weechat_commands.adoc
+++ b/doc/en/autogen/user/weechat_commands.adoc
@@ -308,9 +308,10 @@ Some variables are replaced in expression, using the format ${variable}, variabl
   9. current date/time (format: "date" or "date:format")
   10. an environment variable (format: "env:XXX")
   11. a ternary operator (format: "if:condition?value_if_true:value_if_false")
-  12. an option (format: "file.section.option")
-  13. a local variable in buffer
-  14. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
+  12. result of an expression with parentheses and operators + - * / // % (format: "calc:xxx")
+  13. an option (format: "file.section.option")
+  14. a local variable in buffer
+  15. a hdata name/variable (the value is automatically converted to string), by default "window" and "buffer" point to current window/buffer.
 Format for hdata can be one of following:
   hdata.var1.var2...: start with a hdata (pointer must be known), and ask variables one after one (other hdata can be followed)
   hdata[list].var1.var2...: start with a hdata using a list, for example:
@@ -337,6 +338,7 @@ Examples (simple strings):
   /eval -n ${if:${info:term_width}>80?big:small} ==> big
   /eval -n ${rev:Hello}                          ==> olleH
   /eval -n ${repeat:5,-}                         ==> -----
+  /eval -n ${calc:(5+2)*3}                       ==> 21
 
 Examples (conditions):
   /eval -n -c ${window.buffer.number} > 2 ==> 0
diff --git a/doc/en/weechat_dev.en.adoc b/doc/en/weechat_dev.en.adoc
index ce45c06e3..26a1030f8 100644
--- a/doc/en/weechat_dev.en.adoc
+++ b/doc/en/weechat_dev.en.adoc
@@ -120,6 +120,7 @@ WeeChat "core" is located in following directories:
 | core/                           | Core functions: entry point, internal structures.
 |    wee-arraylist.c              | Array lists.
 |    wee-backtrace.c              | Display a backtrace after a crash.
+|    wee-calc.c                   | Calculate result of expressions.
 |    wee-command.c                | WeeChat core commands.
 |    wee-completion.c             | Default completions.
 |    wee-config-file.c            | Configuration file management.
diff --git a/doc/en/weechat_plugin_api.en.adoc b/doc/en/weechat_plugin_api.en.adoc
index f076adcd1..3a16f07c8 100644
--- a/doc/en/weechat_plugin_api.en.adoc
+++ b/doc/en/weechat_plugin_api.en.adoc
@@ -2148,7 +2148,7 @@ str3 = weechat.string_input_for_buffer("//test")  # "/test"
 
 ==== string_eval_expression
 
-_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8 and 2.0._
+_WeeChat ≥ 0.4.0, updated in 0.4.2, 0.4.3, 1.0, 1.1, 1.2, 1.3, 1.6, 1.8, 2.0 and 2.7._
 
 Evaluate an expression and return result as a string.
 Special variables with format `+${variable}+` are expanded (see table below).
@@ -2535,6 +2535,23 @@ expanded to last):
   `+${if:${info:term_width}>80?big:small}+` |
   `+big+`
 
+| `+${calc:xxx}+` +
+  (_WeeChat ≥ 2.7_) |
+  Result of expression, where parentheses and the following operators are
+  supported: +
+  `+`: addition +
+  `-`: subtraction +
+  `*`: multiplication +
+  `/`: division +
+  `//`: result of division without fractional part +
+  `%`: remainder of division. |
+  `+${calc:5+2*3}+` +
+  `+${calc:(5+2)*3}+` +
+  `+${calc:9.2%3}+` |
+  `+11+` +
+  `+21+` +
+  `+0.2+`
+
 | `+${sec.data.name}+` |
   Value of the secured data `name`. |
   `+${sec.data.freenode_pass}+` |