From 873c97a1206c37de58a56d4b5b3a23c5fbed8c65 Mon Sep 17 00:00:00 2001
From: Michael Zhang <mail@mzhang.io>
Date: Tue, 6 Jul 2021 00:39:06 -0500
Subject: [PATCH] initial version

---
 .gitignore  |   1 +
 Cargo.lock  | 464 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 Cargo.toml  |  12 ++
 src/main.rs |  69 ++++++++
 4 files changed, 546 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.lock
 create mode 100644 Cargo.toml
 create mode 100644 src/main.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..836605c
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,464 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
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+checksum = "1e37cfd5e7657ada45f742d6e99ca5788580b5c529dc78faf11ece6dc702656f"
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+ "memchr",
+]
+
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+ "winapi",
+]
+
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+
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+ "hermit-abi",
+ "libc",
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+ "atty",
+ "bitflags",
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+ "textwrap",
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+ "clap",
+ "entities",
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+ "pest",
+ "pest_derive",
+ "regex",
+ "shell-words",
+ "twoway",
+ "typed-arena",
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+ "xdg",
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+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..e5862ac
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "markout"
+version = "0.1.0"
+authors = ["Michael Zhang <mail@mzhang.io>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0.41"
+comrak = "0.10.1"
+structopt = "0.3.21"
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..1b89f0a
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,69 @@
+use std::fs::File;
+use std::io::{Read, self, Write};
+use std::path::PathBuf;
+
+use anyhow::{Context, Result};
+use comrak::{
+    nodes::{AstNode, NodeValue},
+    parse_document, Arena, ComrakOptions,
+};
+use structopt::StructOpt;
+
+#[derive(Debug, StructOpt)]
+struct Opt {
+    /// The language to filter for
+    #[structopt(long = "lang", short = "l")]
+    lang: Option<String>,
+
+    /// The file to extract from
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let opt = Opt::from_args();
+
+    let contents = {
+        let mut file = File::open(&opt.file)
+            .with_context(|| format!("could not open target file {:?}", opt.file))?;
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)
+            .with_context(|| format!("could not read target file {:?}", opt.file))?;
+        contents
+    };
+
+    let mut stdout = io::stdout();
+
+    let arena = Arena::new();
+    let ast_node = parse_document(&arena, &contents, &ComrakOptions::default());
+    visit_ast(&opt, &mut stdout, ast_node)?;
+
+    Ok(())
+}
+
+fn visit_ast<'a, W: Write>(opt: &Opt, out: &mut W, node: &'a AstNode<'a>) -> Result<()> {
+    let ast = node.data.borrow();
+    match &ast.value {
+        NodeValue::CodeBlock(code_block) => {
+            let should_emit = match &opt.lang {
+                Some(lang) => lang.as_bytes() == &code_block.info,
+                None => true,
+            };
+
+            if should_emit {
+                out.write(&code_block.literal)?;
+            }
+        }
+        NodeValue::List(_) | NodeValue::Item(_) | NodeValue::Document => {
+            // recurse
+            for child in node.children() {
+                visit_ast(opt, out, child)?;
+            }
+        }
+        NodeValue::Heading(_) | NodeValue::BlockQuote | NodeValue::Paragraph => {
+            // don't do anything
+        }
+        _ => todo!("unsupported type {:?}", ast.value),
+    }
+
+    Ok(())
+}