Helm: search within buffer feature?

Question

A pretty basic Helm question. What is the Helm window/command/feature that lets us search for text (preferably using regexp) within any type of buffer (i.e., including read-only such as w3m)?

In other words, I'm looking for Helm's equivalent of Emacs' native commands for isearch-forward (C-s) / isearch-backward (C-r).

To illustrate: after invoking one of the native isearch commands (C-s or C-r), we can exit search mode in one of two ways:

1. we can exit and return to original point (via C-g), or

2. we can exit and continue browsing buffer from current point i.e., from the currently-matched text (via RET among others).

I'm looking for the second of these two options.

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Here's what I've tried so far:

• helm-regexp: this is the closest thing to what I'm looking for but it only performs the equivalent of C-s/C-r + C-g (i.e., it takes us back to the original point; no option for terminating the search and continuing to browse the buffer from the currently matched point).

• helm-do-grep: it seems like this is only for searching for text within files (i.e., doesn't work on w3m)

• helm-buffer-run-grep / -zgrep: running this command/function results in an error message in the mini-buffer: Running helm command outside of context

• when helm-mode is enabled, invoking C-s or C-r brings up Emacs' native isearch feature (it isn't replaced by Helm's interface). (maybe there's a setting we can change so Helm can take over this command? i.e., similar to how Helm takes over the native command for write-file (C-x C-w) which can be used to rename a file in an open buffer. just brainstorming.)

Answer 1

You can use helm-occur as a tool that comes with the basic helm module for this. But to me, one of the best helm based tools for buffer searching is Shingo Fukuyama's helm-swoop. You can get it from github and via MELPA. It has your required functionality of being able to drop your point at the position of the match (which can be a regexp). But you can also use C-g to have the cursor back where you started.

On the helm-swoop github page you'll find a whole bunch of other useful functions that this package offers (including multi-buffer searches by helm-multi-swoop and the ability of editing the lines of the results, so that the changes are applied to the underlying buffer).

Answer 2

You can use helm-occur to see all of the lines that contain matches for your search pattern. You can use C-n and C-p to navigate the list, and then press RET to close the Helm buffer and jump your cursor to the matching line.

I like to enable helm-follow-mode when I use helm-occur so that the source window always shows the context of currently-selected match. You can enable follow-mode automatically as follows:

(require 'helm-config)

(defvar my-helm-follow-sources ()
  "List of sources for which helm-follow-mode should be enabled")

;; Use helm-follow-mode for the following sources:
(add-to-list 'my-helm-follow-sources 'helm-source-occur)

(defun my-helm-set-follow ()
  "Enable helm-follow-mode for the sources specified in the list
variable `my-helm-follow-sources'. This function is meant to
be run during `helm-initialize' and should be added to the hook
`helm-before-initialize-hook'."
  (mapc (lambda (source)
          (when (memq source my-helm-follow-sources)
            (helm-attrset 'follow 1 (symbol-value source))))
        helm-sources))

;; Add hook to enable helm-follow mode for specified helm 
(add-hook 'helm-before-initialize-hook 'my-helm-set-follow)