Move part of parser into its own crate to limit recompilation times

1 files changed, 34 insertions, 0 deletions

diff --git a/dhall_parser/build.rs b/dhall_parser/build.rs
new file mode 100644
index 0000000..6001efe
--- /dev/null
+++ b/dhall_parser/build.rs
@@ -0,0 +1,34 @@
+use std::fs::File;
+use std::io::{Read,Write,BufReader,BufRead};
+use std::collections::HashMap;
+
+use abnf_to_pest::{PestRuleSettings, abnf_to_pest};
+
+fn main() -> std::io::Result<()> {
+    let abnf_path = "../dhall-lang/standard/dhall.abnf";
+    let visibility_path = "src/dhall.pest.visibility";
+    let pest_path = "src/dhall.pest";
+    println!("cargo:rerun-if-changed={}", abnf_path);
+    println!("cargo:rerun-if-changed={}", visibility_path);
+
+    let mut file = File::open(abnf_path)?;
+    let mut data = Vec::new();
+    file.read_to_end(&mut data)?;
+    data.push('\n' as u8);
+
+    let mut rule_settings: HashMap<String, PestRuleSettings> = HashMap::new();
+    for line in BufReader::new(File::open(visibility_path)?).lines() {
+        let line = line?;
+        if line.len() >= 2 && &line[0..2] == "# " {
+            rule_settings.insert(line[2..].into(), PestRuleSettings { visible: false, ..Default::default() });
+        } else {
+            rule_settings.insert(line, PestRuleSettings { visible: true, ..Default::default() });
+        }
+    }
+
+    let mut file = File::create(pest_path)?;
+    writeln!(&mut file, "{}", abnf_to_pest(&data, &rule_settings)?)?;
+    writeln!(&mut file, "final_expression = _{{ SOI ~ complete_expression ~ EOI }}")?;
+
+    Ok(())
+}