added prompt template for file context without truncation

crates/ai/src/templates/file_context.rs

@@ -0,0 +1,85 @@
+use language::ToOffset;
+
+use crate::templates::base::PromptArguments;
+use crate::templates::base::PromptTemplate;
+use std::fmt::Write;
+
+pub struct FileContext {}
+
+impl PromptTemplate for FileContext {
+    fn generate(
+        &self,
+        args: &PromptArguments,
+        max_token_length: Option<usize>,
+    ) -> anyhow::Result<(String, usize)> {
+        let mut prompt = String::new();
+
+        // Add Initial Preamble
+        // TODO: Do we want to add the path in here?
+        writeln!(
+            prompt,
+            "The file you are currently working on has the following content:"
+        )
+        .unwrap();
+
+        let language_name = args
+            .language_name
+            .clone()
+            .unwrap_or("".to_string())
+            .to_lowercase();
+        writeln!(prompt, "```{language_name}").unwrap();
+
+        if let Some(buffer) = &args.buffer {
+            let mut content = String::new();
+
+            if let Some(selected_range) = &args.selected_range {
+                let start = selected_range.start.to_offset(buffer);
+                let end = selected_range.end.to_offset(buffer);
+
+                writeln!(
+                    prompt,
+                    "{}",
+                    buffer.text_for_range(0..start).collect::<String>()
+                )
+                .unwrap();
+
+                if start == end {
+                    writeln!(prompt, "<|START|>").unwrap();
+                } else {
+                    writeln!(prompt, "<|START|").unwrap();
+                }
+
+                writeln!(
+                    prompt,
+                    "{}",
+                    buffer.text_for_range(start..end).collect::<String>()
+                )
+                .unwrap();
+                if start != end {
+                    writeln!(prompt, "|END|>").unwrap();
+                }
+
+                writeln!(
+                    prompt,
+                    "{}",
+                    buffer.text_for_range(end..buffer.len()).collect::<String>()
+                )
+                .unwrap();
+
+                writeln!(prompt, "```").unwrap();
+
+                if start == end {
+                    writeln!(prompt, "In particular, the user's cursor is currently on the '<|START|>' span in the above content, with no text selected.").unwrap();
+                } else {
+                    writeln!(prompt, "In particular, the user has selected a section of the text between the '<|START|' and '|END|>' spans.").unwrap();
+                }
+            } else {
+                // If we dont have a selected range, include entire file.
+                writeln!(prompt, "{}", &buffer.text()).unwrap();
+            }
+        }
+
+        let token_count = args.model.count_tokens(&prompt)?;
+        anyhow::Ok((prompt, token_count))
+    }
+}