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# erl_comment_scan (syntax_tools v4.1)

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Functions for reading comment lines from Erlang source code.

## Summary

### Types

comment()
commentLine()

### Functions

file(Name)

Extracts comments from an Erlang source code file.

join_lines/1

join_lines(CommentLines) ->

scan_lines(Text)

Extracts individual comment lines from a source code string.

string(Text)

Extracts comments from a string containing Erlang source code.

## Types

# comment()

    -type comment() ::
              {Line :: integer(), Column :: integer(), Indentation :: integer(), Text :: [string()]}.

# commentLine()

(not exported)

    -type commentLine() :: {Line :: integer(), Column :: integer(), Indent :: integer(), Text :: string()}.

## Functions

# file(Name)

    -spec file(file:filename()) -> [comment()].

Extracts comments from an Erlang source code file.

Returns a list of entries representing multi-line comments, listed in order of increasing line-numbers. For each entry, `Text` is a list of strings representing the consecutive comment lines in top-down order; the strings contain all characters following (but not including) the first comment-introducing `%` character on the line, up to (but not including) the line-terminating newline.

Furthermore, `Line` is the line number and `Column` the left column of the comment (that is, the column of the comment-introducing `%` character). `Indent` is the indentation (or padding), measured in character positions between the last non-whitespace character before the comment (or the left margin), and the left column of the comment. `Line` and `Column` are always positive integers, and `Indentation` is a nonnegative integer.

Evaluation exits with reason `{read, Reason}` if a read error occurred, where `Reason` is an atom corresponding to a Posix error code; see the module `//kernel/file` for details.

# join_lines/1

    -spec join_lines([commentLine()]) -> [comment()].

join_lines(CommentLines) ->

Joins individual comment lines into multi-line comments.

The input is a list of entries representing individual comment lines, in order of decreasing line-numbers; see `scan_lines/1` for details. The result is a list of entries representing multi-line comments, still listed in order of decreasing line-numbers, but where for each entry, `Text` is a list of consecutive comment lines in order of increasing line-numbers (that is, top-down).

See also: `scan_lines/1`.

# scan_lines(Text)

    -spec scan_lines(string()) -> [commentLine()].

Extracts individual comment lines from a source code string.

Returns a list of comment lines found in the text, listed in order of decreasing line-numbers, that is, the last comment line in the input is first in the resulting list. `Text` is a single string, containing all characters following (but not including) the first comment-introducing `%` character on the line, up to (but not including) the line-terminating newline. For details on `Line`, `Column` and `Indent`, see `file/1`.

# string(Text)

    -spec string(string()) -> [comment()].

Extracts comments from a string containing Erlang source code.

Except for reading directly from a string, the behavior is the same as for `file/1`.

See also: `file/1`.