// Copyright 2020 The Jujutsu Authors//// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at//// https://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License. use jj_lib::rewrite::merge_commit_trees;use tracing::instrument; use crate::cli_util::{CommandHelper, RevisionArg};use crate::command_error::CommandError;use crate::diff_util::{diff_formats_for, show_diff, DiffFormatArgs};use crate::ui::Ui; /// Compare file contents between two revisions////// With the `-r` option, which is the default, shows the changes compared to/// the parent revision. If there are several parent revisions (i.e., the given/// revision is a merge), then they will be merged and the changes from the/// result to the given revision will be shown.////// With the `--from` and/or `--to` options, shows the difference from/to the/// given revisions. If either is left out, it defaults to the working-copy/// commit. For example, `jj diff --from main` shows the changes from "main"/// (perhaps a branch name) to the working-copy commit.#[derive(clap::Args, Clone, Debug)]pub(crate) struct DiffArgs {    /// Show changes in this revision, compared to its parent(s)    ///    /// If the revision is a merge commit, this shows changes *from* the    /// automatic merge of the contents of all of its parents *to* the contents    /// of the revision itself.    #[arg(long, short)]    revision: Option<RevisionArg>,    /// Show changes from this revision    #[arg(long, conflicts_with = "revision")]    from: Option<RevisionArg>,    /// Show changes to this revision    #[arg(long, conflicts_with = "revision")]    to: Option<RevisionArg>,    /// Restrict the diff to these paths    #[arg(value_hint = clap::ValueHint::AnyPath)]    paths: Vec<String>,    #[command(flatten)]    format: DiffFormatArgs,} #[instrument(skip_all)]pub(crate) fn cmd_diff(    ui: &mut Ui,    command: &CommandHelper,    args: &DiffArgs,) -> Result<(), CommandError> {    let workspace_command = command.workspace_helper(ui)?;    let from_tree;    let to_tree;    if args.from.is_some() || args.to.is_some() {        let from = workspace_command.resolve_single_rev(args.from.as_deref().unwrap_or("@"))?;        from_tree = from.tree()?;        let to = workspace_command.resolve_single_rev(args.to.as_deref().unwrap_or("@"))?;        to_tree = to.tree()?;    } else {        let commit =            workspace_command.resolve_single_rev(args.revision.as_deref().unwrap_or("@"))?;        let parents = commit.parents();        from_tree = merge_commit_trees(workspace_command.repo().as_ref(), &parents)?;        to_tree = commit.tree()?    }    let matcher = workspace_command.matcher_from_values(&args.paths)?;    let diff_formats = diff_formats_for(command.settings(), &args.format)?;    ui.request_pager();    show_diff(        ui,        ui.stdout_formatter().as_mut(),        &workspace_command,        &from_tree,        &to_tree,        matcher.as_ref(),        &diff_formats,    )?;    Ok(())}