refactor(tvix/derivation): refactor the derivation serialization

This refactors the code to serialize a derivation. The original code
has beed moved to seperate crates for better code structure.

Change-Id: I3b1a6b134428fcbc9930c330bced8ec3610cfb4c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7733
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/derivation/src/write.rs

@@ -0,0 +1,174 @@
+use crate::output::Output;
+use crate::string_escape::escape_string;
+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<&String>,
+) -> 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)?;
+        }
+
+        // TODO(jrhahn) option to strip output
+        let elements = vec![
+            output_name,
+            &output.path,
+            &output.hash_algorithm,
+            &output.hash,
+        ];
+
+        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, Vec<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().collect(),
+        )?;
+
+        writer.write_char(PAREN_CLOSE)?;
+    }
+
+    writer.write_char(BRACKET_CLOSE)?;
+
+    Ok(())
+}
+
+pub fn write_input_sources(
+    writer: &mut impl Write,
+    input_sources: Vec<String>,
+) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    write_array_elements(
+        writer,
+        true,
+        &BRACKET_OPEN.to_string(),
+        &BRACKET_CLOSE.to_string(),
+        input_sources.iter().collect(),
+    )?;
+
+    Ok(())
+}
+
+pub fn write_platfrom(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: Vec<String>) -> Result<(), fmt::Error> {
+    writer.write_char(COMMA)?;
+    write_array_elements(
+        writer,
+        true,
+        &BRACKET_OPEN.to_string(),
+        &BRACKET_CLOSE.to_string(),
+        arguments.iter().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)?;
+        }
+
+        // TODO(jrhahn) add strip option
+        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(())
+}