Rewrite properties
Comby has convenient built-in properties to transform and substitute matched
values for certain use cases that commonly crop up when rewriting code. For
example, :[hole].Capitalize will capitalize a string matched by hole (if
possible).
echo 'these are words 123' | comby -stdin ':[[x]]' ':[[x]].Capitalize' -lang .txt
--- /dev/null
+++ /dev/null
@@ -1,1 +1,1 @@
-these are words 123
+These Are Words 123
Properties are recognized in the rewrite template and substituted according to the predefined behavior. Property accesses cannot be chained. Below are the current built-in properties.
String converters
| Property | Behavior |
|---|---|
.lowercase | Convert letters to lowercase |
.UPPERCASE | Convert letters to uppercase |
.Capitalize | Capitalize the first character if it is a letter |
.uncapitalize | Lowercase the first character if it is a letter |
.UPPER_SNAKE_CASE | Convert camelCase to snake_case (each capital letter in camelCase gets a _ prepended). Then uppercase letters. |
.lower_snake_case | Convert camelCase to snake_case (each capital letter in camelCase gets a _ prepended). Then lowercase letters. |
.UpperCamelCase | Convert snake_case to CamelCase (each letter after _ in snake_case is capitalized, and the _ removed). Then capitalize the first character. |
.lowerCamelCase | Convert snake_case to CamelCase (each letter after _ in snake_case is capitalized, and the _ removed). Then lowercase the first character. |
Sizes
| Property | Behavior |
|---|---|
.length | Substitute the number of characters of the hole value |
.lines | Substitute the number of lines of the hole value |
Positions
| Property | Behavior |
|---|---|
.line | Substitute the starting line number of this hole |
.line.start | Alias of .line |
.line.end | Substitute the ending line number of this hole |
.column | Substitute the starting column number of this hole (also known as character) |
.column.start | Alias of .column |
.column.end | Substitute the ending column number of this hole |
.offset | Substitute the starting byte offset of this hole in the file |
.offset.start | Alias of .offset |
.offset.end | Substitute the ending byte offset of this hole in the file |
Note: only .offset is available in the playground. .line and
.column are currently only supported on the command-line, and on files (not
via -stdin).
File context
| Property | Behavior |
|---|---|
.file | Substitute the absolute file path of the file where this hole matched |
.file.path | Alias of .file |
.file.name | Substitute the file name of the file where this hole matched (basename) |
.file.directory | Substitute the file directory of the file where hole matched (dirname) |
Use on the command line to see this in action.
Identity (for escaping property names)
| Property | Behavior |
|---|---|
.value | Substitute the text value of this hole (for escaping, see below) |
Resolving clashes with property names
Let’s say you want to literally insert the text .length after a hole. We
can’t use :[hole].length because that reserved syntax will substitute the
length of the match, and not insert the text .length. To resolve a clash like this,
simply use :[hole].value instead of :[hole] to substitute the value of
:[hole]. Then, append .length to the template. This will cause the .length,
to be interpreted literally:
echo 'a word' | comby -stdin ':[[x]]' ':[x].value.length is :[x].length' -lang .txt
--- /dev/null
+++ /dev/null
@@ -1,1 +1,1 @@
-a word
+a.length is 1 word.length is 4
The way this works is that :[hole].value acts as an escape sequence so that any conflicting .<property> can be interpreted
literally by simply appending it to :[hole].value.