From 94cfb806114c1db87aa7e8d345a9df88f942e227 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Sat, 27 Jan 2024 17:38:12 +0200
Subject: [PATCH] analysis/cdecl: add a way to dump a "pseudo-Rust" view of all
 parsed `CDecl`s.

---
 analysis/src/cdecl.rs         | 85 +++++++++++++++++++++++++++++++++++
 analysis/src/lib.rs           | 36 +++++++++++++++
 generator-rewrite/src/main.rs |  3 ++
 3 files changed, 124 insertions(+)

diff --git a/analysis/src/cdecl.rs b/analysis/src/cdecl.rs
index ddc88ea4a..105ef89fa 100644
--- a/analysis/src/cdecl.rs
+++ b/analysis/src/cdecl.rs
@@ -390,4 +390,89 @@ impl<'a> CDecl<'a> {
             bitfield_width,
         })
     }
+
+    pub fn to_pseudo_rust(&self) -> String {
+        self.to_pseudo_rust_with_external_len(None)
+    }
+    pub fn to_pseudo_rust_with_external_len(&self, external_len: Option<&str>) -> String {
+        let CDecl {
+            ty,
+            name,
+            bitfield_width,
+        } = self;
+        let decl = format!(
+            "{name}: {}",
+            ty.to_pseudo_rust_with_external_len(external_len)
+        );
+        match bitfield_width {
+            Some(width) => format!("#[bitfield({width})] {decl}"),
+            None => decl,
+        }
+    }
+}
+
+impl CType<'_> {
+    pub fn to_pseudo_rust_with_external_len(&self, external_len: Option<&str>) -> String {
+        if let Some(len) = external_len {
+            match self {
+                CType::Ptr {
+                    implicit_for_decay: false,
+                    is_const,
+                    pointee,
+                } => {
+                    let const_or_mut = if *is_const { "const" } else { "mut" };
+                    format!("*{const_or_mut} [{}; dyn {len}]", pointee.to_pseudo_rust())
+                }
+                _ => unreachable!(),
+            }
+        } else {
+            self.to_pseudo_rust()
+        }
+    }
+    pub fn to_pseudo_rust(&self) -> String {
+        match self {
+            &CType::Base(CBaseType { struct_tag, name }) => {
+                if struct_tag {
+                    format!("/*struct*/{name}")
+                } else {
+                    name.to_string()
+                }
+            }
+            CType::Ptr {
+                implicit_for_decay,
+                is_const,
+                pointee,
+            } => {
+                if let CType::Func { ret_ty, params } = &**pointee {
+                    assert!(!implicit_for_decay);
+                    assert!(!is_const);
+                    let params = if params.is_empty() {
+                        "".to_string()
+                    } else {
+                        params.iter().fold("\n".to_string(), |params, param| {
+                            params + "    " + &param.to_pseudo_rust() + ",\n"
+                        })
+                    };
+                    format!(
+                        "unsafe extern fn({params}){}",
+                        ret_ty
+                            .as_ref()
+                            .map(|ty| format!(" -> {}", ty.to_pseudo_rust()))
+                            .unwrap_or_default()
+                    )
+                } else {
+                    let const_or_mut = if *is_const { "const" } else { "mut" };
+                    format!("*{const_or_mut} {}", pointee.to_pseudo_rust())
+                }
+            }
+            CType::Array { element, len } => {
+                let len = match len {
+                    CArrayLen::Named(name) => name.to_string(),
+                    CArrayLen::Literal(len) => len.to_string(),
+                };
+                format!("[{}; {len}]", element.to_pseudo_rust())
+            }
+            CType::Func { .. } => unreachable!(),
+        }
+    }
 }
diff --git a/analysis/src/lib.rs b/analysis/src/lib.rs
index 81a7707de..09c41fc9d 100644
--- a/analysis/src/lib.rs
+++ b/analysis/src/lib.rs
@@ -1,3 +1,4 @@
+mod cdecl;
 mod xml;
 
 use std::{fs, path::Path};
@@ -17,6 +18,41 @@ impl Analysis {
             video: Library::new(vulkan_headers_path.join("registry/video.xml")),
         }
     }
+
+    pub fn dump_as_pseudo_rust(&self) {
+        for fp in &self.vk._xml.funcpointers {
+            eprintln!(
+                "type {} = {};",
+                fp.c_decl.name,
+                fp.c_decl.ty.to_pseudo_rust()
+            );
+        }
+        for st in &self.vk._xml.structs {
+            eprintln!("struct {} {{", st.name);
+            for m in &st.members {
+                let len = m.altlen.as_deref().or(m.len.as_deref());
+                eprint!("    {}", m.c_decl.to_pseudo_rust_with_external_len(len));
+                if let Some(val) = &m.values {
+                    eprint!(" = {val}");
+                }
+                eprintln!(",");
+            }
+            eprintln!("}}");
+        }
+        for cmd in &self.vk._xml.commands {
+            eprintln!("unsafe extern fn {}(", cmd.name);
+            for p in &cmd.params {
+                let len = p.altlen.as_deref().or(p.len.as_deref());
+                eprint!("    {}", p.c_decl.to_pseudo_rust_with_external_len(len));
+                eprintln!(",");
+            }
+            eprint!(")");
+            if let Some(ret_ty) = &cmd.return_type {
+                eprint!(" -> {}", ret_ty.to_pseudo_rust());
+            }
+            eprintln!(";");
+        }
+    }
 }
 
 #[derive(Debug)]
diff --git a/generator-rewrite/src/main.rs b/generator-rewrite/src/main.rs
index fb5ff861d..cc14b0fbf 100644
--- a/generator-rewrite/src/main.rs
+++ b/generator-rewrite/src/main.rs
@@ -4,4 +4,7 @@ fn main() {
     tracing_subscriber::fmt::init();
     let _analysis = Analysis::new("generator/Vulkan-Headers");
     // dbg!(_analysis);
+    if false {
+        _analysis.dump_as_pseudo_rust();
+    }
 }