Merge #924

924: Improve show syntax tree r=matklad a=vipentti

This implements some of the features discussed in #820. 

You can now select a range of syntax in a file and then use "Show Syntax Tree" to show its syntax. In addition you can select a range of syntax that is inside a string (typically test cases) and show its syntax as well.

Previous behavior is still available, simply use "Show Syntax Tree" without a selection, and you get the live updating syntax tree. Additionally now the live updating tree will update when the active file is changed. Previously you had to type something in the new file to get the syntax tree to update.

Co-authored-by: Ville Penttinen <[email protected]>

2 files changed, 91 insertions, 3 deletions

diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index 6546d0644..b8a4adbce 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -32,13 +32,14 @@ mod references;
 mod impls;
 mod assists;
 mod diagnostics;
+mod syntax_tree;
 
 #[cfg(test)]
 mod marks;
 
 use std::sync::Arc;
 
-use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit, AstNode};
+use ra_syntax::{SourceFile, TreeArc, TextRange, TextUnit};
 use ra_text_edit::TextEdit;
 use ra_db::{
     SourceDatabase, CheckCanceled,
@@ -245,8 +246,8 @@ impl Analysis {
 
     /// Returns a syntax tree represented as `String`, for debug purposes.
     // FIXME: use a better name here.
-    pub fn syntax_tree(&self, file_id: FileId) -> String {
-        self.db.parse(file_id).syntax().debug_dump()
+    pub fn syntax_tree(&self, file_id: FileId, text_range: Option<TextRange>) -> String {
+        syntax_tree::syntax_tree(&self.db, file_id, text_range)
     }
 
     /// Returns an edit to remove all newlines in the range, cleaning up minor
diff --git a/crates/ra_ide_api/src/syntax_tree.rs b/crates/ra_ide_api/src/syntax_tree.rs
new file mode 100644
index 000000000..bbe9222b4
--- /dev/null
+++ b/crates/ra_ide_api/src/syntax_tree.rs
@@ -0,0 +1,87 @@
+use ra_db::SourceDatabase;

+use crate::db::RootDatabase;

+use ra_syntax::{

+    SourceFile, SyntaxNode, TextRange, AstNode,

+    algo::{self, visit::{visitor, Visitor}}, ast::{self, AstToken}

+};

+

+pub use ra_db::FileId;

+

+pub(crate) fn syntax_tree(

+    db: &RootDatabase,

+    file_id: FileId,

+    text_range: Option<TextRange>,

+) -> String {

+    if let Some(text_range) = text_range {

+        let file = db.parse(file_id);

+        let node = algo::find_covering_node(file.syntax(), text_range);

+

+        if let Some(tree) = syntax_tree_for_string(node, text_range) {

+            return tree;

+        }

+

+        node.debug_dump()

+    } else {

+        db.parse(file_id).syntax().debug_dump()

+    }

+}

+

+/// Attempts parsing the selected contents of a string literal

+/// as rust syntax and returns its syntax tree

+fn syntax_tree_for_string(node: &SyntaxNode, text_range: TextRange) -> Option<String> {

+    // When the range is inside a string

+    // we'll attempt parsing it as rust syntax

+    // to provide the syntax tree of the contents of the string

+    visitor()

+        .visit(|node: &ast::String| syntax_tree_for_token(node, text_range))

+        .visit(|node: &ast::RawString| syntax_tree_for_token(node, text_range))

+        .accept(node)?

+}

+

+fn syntax_tree_for_token<T: AstToken>(node: &T, text_range: TextRange) -> Option<String> {

+    // Range of the full node

+    let node_range = node.syntax().range();

+    let text = node.text().to_string();

+

+    // We start at some point inside the node

+    // Either we have selected the whole string

+    // or our selection is inside it

+    let start = text_range.start() - node_range.start();

+

+    // how many characters we have selected

+    let len = text_range.len().to_usize();

+

+    let node_len = node_range.len().to_usize();

+

+    let start = start.to_usize();

+

+    // We want to cap our length

+    let len = len.min(node_len);

+

+    // Ensure our slice is inside the actual string

+    let end = if start + len < text.len() { start + len } else { text.len() - start };

+

+    let text = &text[start..end];

+

+    // Remove possible extra string quotes from the start

+    // and the end of the string

+    let text = text

+        .trim_start_matches('r')

+        .trim_start_matches('#')

+        .trim_start_matches('"')

+        .trim_end_matches('#')

+        .trim_end_matches('"')

+        .trim()

+        // Remove custom markers

+        .replace("<|>", "");

+

+    let parsed = SourceFile::parse(&text);

+

+    // If the "file" parsed without errors,

+    // return its syntax

+    if parsed.errors().is_empty() {

+        return Some(parsed.syntax().debug_dump());

+    }

+

+    None

+}