1 files changed, 58 insertions, 0 deletions
diff --git a/third_party/rust/rust_decimal/build.rs b/third_party/rust/rust_decimal/build.rs
new file mode 100644
index 0000000000..604a77c792
--- /dev/null
+++ b/third_party/rust/rust_decimal/build.rs
@@ -0,0 +1,58 @@
+use std::fmt::Write;
+use std::{fs, path::PathBuf};
+
+fn main() {
+    println!("cargo:rerun-if-changed=README.md");
+    let readme = fs::read_to_string("README.md").unwrap();
+    let output = PathBuf::from(std::env::var("OUT_DIR").unwrap()).join("README-lib.md");
+    let contents = prepare(&readme).unwrap();
+    fs::write(output, contents).unwrap();
+}
+
+fn prepare(readme: &str) -> Result<String, Box<dyn std::error::Error>> {
+    // This is a naive implementation to get things off the ground.
+    // We just do a few things for this at the moment:
+    // 1. Strip header stuff
+    // 2. Replace the build document link
+    // 3. Replace serde examples with ignore flags (to avoid feature flagging configuration in docs)
+    let mut cleaned = String::new();
+    let mut body = false;
+    let mut feature_section = false;
+    let mut feature = String::new();
+    for line in readme.lines() {
+        if !body {
+            if line.starts_with("[docs]") {
+                body = true;
+            }
+            continue;
+        }
+
+        // Add the line as is, unless it contains "(BUILD.md)"
+        if line.contains("(BUILD.md)") {
+            write!(
+                cleaned,
+                "{}",
+                &line.replace(
+                    "(BUILD.md)",
+                    "(https://github.com/paupino/rust-decimal/blob/master/BUILD.md)",
+                )
+            )?;
+        } else if feature_section && line.starts_with("```rust") {
+            // This is a bit naive, but it's to make the Serde examples cleaner. Should probably
+            // be a bit more "defensive" here.
+            writeln!(cleaned, "```rust")?;
+            writeln!(cleaned, "# use rust_decimal::Decimal;")?;
+            writeln!(cleaned, "# use serde::{{Serialize, Deserialize}};")?;
+            write!(cleaned, "# #[cfg(features = \"{}\")]", feature)?;
+        } else {
+            if !feature_section && line.starts_with("## Features") {
+                feature_section = true;
+            } else if feature_section && line.starts_with("### ") {
+                feature = line.replace("### ", "").replace('`', "");
+            }
+            write!(cleaned, "{}", line)?;
+        }
+        writeln!(cleaned)?;
+    }
+    Ok(cleaned)
+}