From 662ab2ecc8e29eb5995b3c162fac869838bea9a2 Mon Sep 17 00:00:00 2001
From: David Lattimore <dml@google.com>
Date: Wed, 17 Jun 2020 16:53:51 +1000
Subject: Allow SSR to match type references, items, paths and patterns

Part of #3186
---
 crates/ra_ssr/src/replacing.rs | 55 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 crates/ra_ssr/src/replacing.rs

(limited to 'crates/ra_ssr/src/replacing.rs')

diff --git a/crates/ra_ssr/src/replacing.rs b/crates/ra_ssr/src/replacing.rs
new file mode 100644
index 000000000..81a5e06a9
--- /dev/null
+++ b/crates/ra_ssr/src/replacing.rs
@@ -0,0 +1,55 @@
+//! Code for applying replacement templates for matches that have previously been found.
+
+use crate::matching::Var;
+use crate::parsing::PatternElement;
+use crate::{Match, SsrMatches};
+use ra_syntax::ast::AstToken;
+use ra_syntax::TextSize;
+use ra_text_edit::TextEdit;
+
+/// Returns a text edit that will replace each match in `matches` with its corresponding replacement
+/// template. Placeholders in the template will have been substituted with whatever they matched to
+/// in the original code.
+pub(crate) fn matches_to_edit(matches: &SsrMatches) -> TextEdit {
+    matches_to_edit_at_offset(matches, 0.into())
+}
+
+fn matches_to_edit_at_offset(matches: &SsrMatches, relative_start: TextSize) -> TextEdit {
+    let mut edit_builder = ra_text_edit::TextEditBuilder::default();
+    for m in &matches.matches {
+        edit_builder.replace(m.range.checked_sub(relative_start).unwrap(), render_replace(m));
+    }
+    edit_builder.finish()
+}
+
+fn render_replace(match_info: &Match) -> String {
+    let mut out = String::new();
+    for r in &match_info.template.tokens {
+        match r {
+            PatternElement::Token(t) => out.push_str(t.text.as_str()),
+            PatternElement::Placeholder(p) => {
+                if let Some(placeholder_value) =
+                    match_info.placeholder_values.get(&Var(p.ident.to_string()))
+                {
+                    let range = &placeholder_value.range.range;
+                    let mut matched_text = placeholder_value.node.text().to_string();
+                    let edit =
+                        matches_to_edit_at_offset(&placeholder_value.inner_matches, range.start());
+                    edit.apply(&mut matched_text);
+                    out.push_str(&matched_text);
+                } else {
+                    // We validated that all placeholder references were valid before we
+                    // started, so this shouldn't happen.
+                    panic!(
+                        "Internal error: replacement referenced unknown placeholder {}",
+                        p.ident
+                    );
+                }
+            }
+        }
+    }
+    for comment in &match_info.ignored_comments {
+        out.push_str(&comment.syntax().to_string());
+    }
+    out
+}
-- 
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