From fe71def43484098a46b6b0cd295525f25003c191 Mon Sep 17 00:00:00 2001
From: Nehal Patel <nehal@alum.mit.edu>
Date: Fri, 17 Mar 2023 15:04:50 -0400
Subject: [PATCH] Create a TranslationUnit by loading ast file (aka precompiled
 header).

---
 src/Clang.jl      |  2 +-
 src/trans_unit.jl | 55 ++++++++++++++++++++++++++++++++++++++++-------
 test/ast.jl       | 17 +++++++++++++++
 test/runtests.jl  |  1 +
 4 files changed, 66 insertions(+), 9 deletions(-)
 create mode 100644 test/ast.jl

diff --git a/src/Clang.jl b/src/Clang.jl
index db9d40c3..86ebbf03 100644
--- a/src/Clang.jl
+++ b/src/Clang.jl
@@ -28,7 +28,7 @@ include("index.jl")
 export Index
 
 include("trans_unit.jl")
-export TranslationUnit, spelling, parse_header, parse_headers
+export TranslationUnit, getTranslationUnitCursor, spelling, parse_header, parse_headers, load_ast
 
 include("cursor.jl")
 export kind, name, spelling, value
diff --git a/src/trans_unit.jl b/src/trans_unit.jl
index 1344ddcf..6824321e 100644
--- a/src/trans_unit.jl
+++ b/src/trans_unit.jl
@@ -6,6 +6,34 @@ Parse the given source file and the translation unit corresponding to that file.
 mutable struct TranslationUnit
     ptr::CXTranslationUnit
     idx::Index
+    
+    function TranslationUnit(
+        ptr::CXTranslationUnit,
+        idx::Index,
+    )
+        @assert ptr != C_NULL 
+        obj = new(ptr, idx)
+        finalizer(obj) do x
+            if x.ptr != C_NULL
+                clang_disposeTranslationUnit(x)
+                x.ptr = C_NULL
+            end
+        end
+        return obj
+    end
+
+    function TranslationUnit(
+        idx::Index,
+        ast_filename::AbstractString,
+    )
+        ptr = clang_createTranslationUnit(
+            idx,
+            ast_filename)
+        @assert ptr != C_NULL "failed to parse file: $ast_filename"
+        return TranslationUnit(ptr, idx)
+    end
+            
+    
     function TranslationUnit(
         idx::Index,
         source_filename,
@@ -25,14 +53,7 @@ mutable struct TranslationUnit
             options,
         )
         @assert ptr != C_NULL "failed to parse file: $source_filename"
-        obj = new(ptr, idx)
-        finalizer(obj) do x
-            if x.ptr != C_NULL
-                clang_disposeTranslationUnit(x)
-                x.ptr = C_NULL
-            end
-        end
-        return obj
+        return TranslationUnit(ptr, idx)
     end
 end
 function TranslationUnit(idx, source, args, unsavedFiles, options)
@@ -143,3 +164,21 @@ function parse_headers(
         parse_header(index, header, args, flags)
     end
 end
+
+"""
+    load_ast(
+        index::Index,
+        ast_file::AbstractString,
+    ) -> TranslationUnit
+Return the [`TranslationUnit`](@ref) for a given precompiled header (aka an "ast file" in clang).
+
+# Arguments
+- `index::Index`: Index.
+- `ast_file::AbstractString`: the ast file to load`.  
+   Ast files can be generated using clang e.g. `clang t.h -emit-ast -o t.pch`
+"""
+function load_ast(
+    index::Index,
+    ast_file::AbstractString)
+    TranslationUnit(index, ast_file)
+end
diff --git a/test/ast.jl b/test/ast.jl
new file mode 100644
index 00000000..35b39c28
--- /dev/null
+++ b/test/ast.jl
@@ -0,0 +1,17 @@
+using Clang
+using Clang.LibClang.Clang_jll
+using Test
+
+@testset "Load AST" begin
+    mktempdir() do dir
+        header = joinpath(dir,"test.h")
+        pch    = joinpath(dir,"test.pch")
+        open(header, "w") do io
+            write(io, "void foo();")
+        end
+        run(`$(clang()) -x c $header -emit-ast -o $pch`);
+        index = Index()
+        tu = load_ast(index, pch)
+        @test tu |> getTranslationUnitCursor |> children |> only |> spelling == "foo"
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index db6213b0..b53573c2 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,6 +1,7 @@
 using Clang
 using Test
 
+include("ast.jl")
 include("generators.jl")
 
 include("test_mpi.jl")