1 files changed, 184 insertions, 0 deletions
diff --git a/tvix/nix-compat/src/derivation/write.rs b/tvix/nix-compat/src/derivation/write.rs
new file mode 100644
index 0000000000..9423ef2e6a
--- /dev/null
+++ b/tvix/nix-compat/src/derivation/write.rs
@@ -0,0 +1,184 @@
+//! This module implements the serialisation of derivations into the
+//! [ATerm][] format used by C++ Nix.
+//!
+//! [ATerm]: http://program-transformation.org/Tools/ATermFormat.html
+
+use crate::derivation::output::Output;
+use crate::derivation::string_escape::escape_string;
+use std::collections::BTreeSet;
+use std::{collections::BTreeMap, fmt, fmt::Write};
+
+pub const DERIVATION_PREFIX: &str = "Derive";
+pub const PAREN_OPEN: char = '(';
+pub const PAREN_CLOSE: char = ')';
+pub const BRACKET_OPEN: char = '[';
+pub const BRACKET_CLOSE: char = ']';
+pub const COMMA: char = ',';
+pub const QUOTE: char = '"';
+
+fn write_array_elements(
+    writer: &mut impl Write,
+    quote: bool,
+    open: &str,
+    closing: &str,
+    elements: Vec<&str>,
+) -> Result<(), fmt::Error> {
+    writer.write_str(open)?;
+
+    for (index, element) in elements.iter().enumerate() {
+        if index > 0 {
+            writer.write_char(COMMA)?;
+        }
+
+        if quote {
+            writer.write_char(QUOTE)?;
+        }
+
+        writer.write_str(element)?;
+
+        if quote {
+            writer.write_char(QUOTE)?;
+        }
+    }
+
+    writer.write_str(closing)?;
+
+    Ok(())
+}
+
+pub fn write_outputs(
+    writer: &mut impl Write,
+    outputs: &BTreeMap<String, Output>,
+) -> Result<(), fmt::Error> {
+    writer.write_char(BRACKET_OPEN)?;
+    for (ii, (output_name, output)) in outputs.iter().enumerate() {
+        if ii > 0 {
+            writer.write_char(COMMA)?;
+        }
+
+        let mut elements: Vec<&str> = vec![output_name, &output.path];
+
+        match &output.hash {
+            Some(hash) => {
+                elements.push(&hash.algo);
+                elements.push(&hash.digest);
+            }
+            None => {
+                elements.push("");
+                elements.push("");
+            }
+        }
+
+        write_array_elements(
+            writer,
+            true,
+            &PAREN_OPEN.to_string(),
+            &PAREN_CLOSE.to_string(),
+            elements,
+        )?
+    }
+    writer.write_char(BRACKET_CLOSE)?;
+
+    Ok(())
+}
+
+pub fn write_input_derivations(
+    writer: &mut impl Write,
+    input_derivations: &BTreeMap<String, BTreeSet<String>>,
+) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    writer.write_char(BRACKET_OPEN)?;
+
+    for (ii, (input_derivation_path, input_derivation)) in input_derivations.iter().enumerate() {
+        if ii > 0 {
+            writer.write_char(COMMA)?;
+        }
+
+        writer.write_char(PAREN_OPEN)?;
+        writer.write_char(QUOTE)?;
+        writer.write_str(input_derivation_path.as_str())?;
+        writer.write_char(QUOTE)?;
+        writer.write_char(COMMA)?;
+
+        write_array_elements(
+            writer,
+            true,
+            &BRACKET_OPEN.to_string(),
+            &BRACKET_CLOSE.to_string(),
+            input_derivation.iter().map(|s| &**s).collect(),
+        )?;
+
+        writer.write_char(PAREN_CLOSE)?;
+    }
+
+    writer.write_char(BRACKET_CLOSE)?;
+
+    Ok(())
+}
+
+pub fn write_input_sources(
+    writer: &mut impl Write,
+    input_sources: &BTreeSet<String>,
+) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+
+    write_array_elements(
+        writer,
+        true,
+        &BRACKET_OPEN.to_string(),
+        &BRACKET_CLOSE.to_string(),
+        input_sources.iter().map(|s| &**s).collect(),
+    )?;
+
+    Ok(())
+}
+
+pub fn write_system(writer: &mut impl Write, platform: &str) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    writer.write_str(escape_string(platform).as_str())?;
+    Ok(())
+}
+
+pub fn write_builder(writer: &mut impl Write, builder: &str) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    writer.write_str(escape_string(builder).as_str())?;
+    Ok(())
+}
+pub fn write_arguments(writer: &mut impl Write, arguments: &[String]) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    write_array_elements(
+        writer,
+        true,
+        &BRACKET_OPEN.to_string(),
+        &BRACKET_CLOSE.to_string(),
+        arguments.iter().map(|s| &**s).collect(),
+    )?;
+
+    Ok(())
+}
+
+pub fn write_enviroment(
+    writer: &mut impl Write,
+    environment: &BTreeMap<String, String>,
+) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    writer.write_char(BRACKET_OPEN)?;
+
+    for (ii, (key, environment)) in environment.iter().enumerate() {
+        if ii > 0 {
+            writer.write_char(COMMA)?;
+        }
+
+        write_array_elements(
+            writer,
+            false,
+            &PAREN_OPEN.to_string(),
+            &PAREN_CLOSE.to_string(),
+            vec![&escape_string(key), &escape_string(environment)],
+        )?;
+    }
+
+    writer.write_char(BRACKET_CLOSE)?;
+
+    Ok(())
+}