Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1610 insertions, 0 deletions

diff --git a/third_party/rust/glsl/src/transpiler/glsl.rs b/third_party/rust/glsl/src/transpiler/glsl.rs
new file mode 100644
index 0000000000..e5244f7e5b
--- /dev/null
+++ b/third_party/rust/glsl/src/transpiler/glsl.rs
@@ -0,0 +1,1610 @@
+//! A GLSL450/GLSL460 transpiler that takes a syntax tree and writes it as a plain raw GLSL
+//! [`String`].
+//!
+//! # Foreword
+//!
+//! This module exports several functions that just transform a part of a syntax tree into its raw
+//! GLSL [`String`] representation.
+//!
+//! > Important note: this module – and actually, any [`transpiler`] module – is not responsible in
+//! > optimizing the syntax tree nor semantically check its validity. This is done in other stages
+//! > of the compilation process.
+//!
+//! In order to achieve that purpose, you could:
+//!
+//! - For each elements in the AST, return a [`String`] or [`Cow<str>`].
+//! - Insert the string representation via a formatter.
+//!
+//! The second solution is better because it lets the user handle the memory the way they want:
+//! they might just use a dynamic buffer that implements [`Write`] or simply pass a `&mut`
+//! [`String`]. It’s up to you.
+//!
+//! # How to use this module
+//!
+//! First, head over to the [`syntax`] module. That module defines the AST items defined by GLSL. This
+//! very module provides you with functions like `show_*` taking the AST item and writing it to a
+//! [`Write`] object. You’re likely to be interested in [`show_translation_unit`] to start with.
+//!
+//! [`Cow<str>`]: std::borrow::Cow
+//! [`Write`]: std::fmt::Write
+//! [`show_translation_unit`]: crate::transpiler::glsl::show_translation_unit
+//! [`syntax`]: crate::syntax
+//! [`transpiler`]: crate::transpiler
+
+use std::fmt::Write;
+
+use crate::syntax;
+
+pub fn show_identifier<F>(f: &mut F, i: &syntax::Identifier)
+where
+  F: Write,
+{
+  let _ = f.write_str(&i.0);
+}
+
+pub fn show_type_name<F>(f: &mut F, t: &syntax::TypeName)
+where
+  F: Write,
+{
+  let _ = f.write_str(&t.0);
+}
+
+pub fn show_type_specifier_non_array<F>(f: &mut F, t: &syntax::TypeSpecifierNonArray)
+where
+  F: Write,
+{
+  match *t {
+    syntax::TypeSpecifierNonArray::Void => {
+      let _ = f.write_str("void");
+    }
+    syntax::TypeSpecifierNonArray::Bool => {
+      let _ = f.write_str("bool");
+    }
+    syntax::TypeSpecifierNonArray::Int => {
+      let _ = f.write_str("int");
+    }
+    syntax::TypeSpecifierNonArray::UInt => {
+      let _ = f.write_str("uint");
+    }
+    syntax::TypeSpecifierNonArray::Float => {
+      let _ = f.write_str("float");
+    }
+    syntax::TypeSpecifierNonArray::Double => {
+      let _ = f.write_str("double");
+    }
+    syntax::TypeSpecifierNonArray::Vec2 => {
+      let _ = f.write_str("vec2");
+    }
+    syntax::TypeSpecifierNonArray::Vec3 => {
+      let _ = f.write_str("vec3");
+    }
+    syntax::TypeSpecifierNonArray::Vec4 => {
+      let _ = f.write_str("vec4");
+    }
+    syntax::TypeSpecifierNonArray::DVec2 => {
+      let _ = f.write_str("dvec2");
+    }
+    syntax::TypeSpecifierNonArray::DVec3 => {
+      let _ = f.write_str("dvec3");
+    }
+    syntax::TypeSpecifierNonArray::DVec4 => {
+      let _ = f.write_str("dvec4");
+    }
+    syntax::TypeSpecifierNonArray::BVec2 => {
+      let _ = f.write_str("bvec2");
+    }
+    syntax::TypeSpecifierNonArray::BVec3 => {
+      let _ = f.write_str("bvec3");
+    }
+    syntax::TypeSpecifierNonArray::BVec4 => {
+      let _ = f.write_str("bvec4");
+    }
+    syntax::TypeSpecifierNonArray::IVec2 => {
+      let _ = f.write_str("ivec2");
+    }
+    syntax::TypeSpecifierNonArray::IVec3 => {
+      let _ = f.write_str("ivec3");
+    }
+    syntax::TypeSpecifierNonArray::IVec4 => {
+      let _ = f.write_str("ivec4");
+    }
+    syntax::TypeSpecifierNonArray::UVec2 => {
+      let _ = f.write_str("uvec2");
+    }
+    syntax::TypeSpecifierNonArray::UVec3 => {
+      let _ = f.write_str("uvec3");
+    }
+    syntax::TypeSpecifierNonArray::UVec4 => {
+      let _ = f.write_str("uvec4");
+    }
+    syntax::TypeSpecifierNonArray::Mat2 => {
+      let _ = f.write_str("mat2");
+    }
+    syntax::TypeSpecifierNonArray::Mat3 => {
+      let _ = f.write_str("mat3");
+    }
+    syntax::TypeSpecifierNonArray::Mat4 => {
+      let _ = f.write_str("mat4");
+    }
+    syntax::TypeSpecifierNonArray::Mat23 => {
+      let _ = f.write_str("mat23");
+    }
+    syntax::TypeSpecifierNonArray::Mat24 => {
+      let _ = f.write_str("mat24");
+    }
+    syntax::TypeSpecifierNonArray::Mat32 => {
+      let _ = f.write_str("mat32");
+    }
+    syntax::TypeSpecifierNonArray::Mat34 => {
+      let _ = f.write_str("mat34");
+    }
+    syntax::TypeSpecifierNonArray::Mat42 => {
+      let _ = f.write_str("mat42");
+    }
+    syntax::TypeSpecifierNonArray::Mat43 => {
+      let _ = f.write_str("mat43");
+    }
+    syntax::TypeSpecifierNonArray::DMat2 => {
+      let _ = f.write_str("dmat2");
+    }
+    syntax::TypeSpecifierNonArray::DMat3 => {
+      let _ = f.write_str("dmat3");
+    }
+    syntax::TypeSpecifierNonArray::DMat4 => {
+      let _ = f.write_str("dmat4");
+    }
+    syntax::TypeSpecifierNonArray::DMat23 => {
+      let _ = f.write_str("dmat23");
+    }
+    syntax::TypeSpecifierNonArray::DMat24 => {
+      let _ = f.write_str("dmat24");
+    }
+    syntax::TypeSpecifierNonArray::DMat32 => {
+      let _ = f.write_str("dmat32");
+    }
+    syntax::TypeSpecifierNonArray::DMat34 => {
+      let _ = f.write_str("dmat34");
+    }
+    syntax::TypeSpecifierNonArray::DMat42 => {
+      let _ = f.write_str("dmat42");
+    }
+    syntax::TypeSpecifierNonArray::DMat43 => {
+      let _ = f.write_str("dmat43");
+    }
+    syntax::TypeSpecifierNonArray::Sampler1D => {
+      let _ = f.write_str("sampler1D");
+    }
+    syntax::TypeSpecifierNonArray::Image1D => {
+      let _ = f.write_str("image1D");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2D => {
+      let _ = f.write_str("sampler2D");
+    }
+    syntax::TypeSpecifierNonArray::Image2D => {
+      let _ = f.write_str("image2D");
+    }
+    syntax::TypeSpecifierNonArray::Sampler3D => {
+      let _ = f.write_str("sampler3D");
+    }
+    syntax::TypeSpecifierNonArray::Image3D => {
+      let _ = f.write_str("image3D");
+    }
+    syntax::TypeSpecifierNonArray::SamplerCube => {
+      let _ = f.write_str("samplerCube");
+    }
+    syntax::TypeSpecifierNonArray::ImageCube => {
+      let _ = f.write_str("imageCube");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DRect => {
+      let _ = f.write_str("sampler2DRect");
+    }
+    syntax::TypeSpecifierNonArray::Image2DRect => {
+      let _ = f.write_str("image2DRect");
+    }
+    syntax::TypeSpecifierNonArray::Sampler1DArray => {
+      let _ = f.write_str("sampler1DArray");
+    }
+    syntax::TypeSpecifierNonArray::Image1DArray => {
+      let _ = f.write_str("image1DArray");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DArray => {
+      let _ = f.write_str("sampler2DArray");
+    }
+    syntax::TypeSpecifierNonArray::Image2DArray => {
+      let _ = f.write_str("image2DArray");
+    }
+    syntax::TypeSpecifierNonArray::SamplerBuffer => {
+      let _ = f.write_str("samplerBuffer");
+    }
+    syntax::TypeSpecifierNonArray::ImageBuffer => {
+      let _ = f.write_str("imageBuffer");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DMS => {
+      let _ = f.write_str("sampler2DMS");
+    }
+    syntax::TypeSpecifierNonArray::Image2DMS => {
+      let _ = f.write_str("image2DMS");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DMSArray => {
+      let _ = f.write_str("sampler2DMSArray");
+    }
+    syntax::TypeSpecifierNonArray::Image2DMSArray => {
+      let _ = f.write_str("image2DMSArray");
+    }
+    syntax::TypeSpecifierNonArray::SamplerCubeArray => {
+      let _ = f.write_str("samplerCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::ImageCubeArray => {
+      let _ = f.write_str("imageCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::Sampler1DShadow => {
+      let _ = f.write_str("sampler1DShadow");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DShadow => {
+      let _ = f.write_str("sampler2DShadow");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DRectShadow => {
+      let _ = f.write_str("sampler2DRectShadow");
+    }
+    syntax::TypeSpecifierNonArray::Sampler1DArrayShadow => {
+      let _ = f.write_str("sampler1DArrayShadow");
+    }
+    syntax::TypeSpecifierNonArray::Sampler2DArrayShadow => {
+      let _ = f.write_str("sampler2DArrayShadow");
+    }
+    syntax::TypeSpecifierNonArray::SamplerCubeShadow => {
+      let _ = f.write_str("samplerCubeShadow");
+    }
+    syntax::TypeSpecifierNonArray::SamplerCubeArrayShadow => {
+      let _ = f.write_str("samplerCubeArrayShadow");
+    }
+    syntax::TypeSpecifierNonArray::ISampler1D => {
+      let _ = f.write_str("isampler1D");
+    }
+    syntax::TypeSpecifierNonArray::IImage1D => {
+      let _ = f.write_str("iimage1D");
+    }
+    syntax::TypeSpecifierNonArray::ISampler2D => {
+      let _ = f.write_str("isampler2D");
+    }
+    syntax::TypeSpecifierNonArray::IImage2D => {
+      let _ = f.write_str("iimage2D");
+    }
+    syntax::TypeSpecifierNonArray::ISampler3D => {
+      let _ = f.write_str("isampler3D");
+    }
+    syntax::TypeSpecifierNonArray::IImage3D => {
+      let _ = f.write_str("iimage3D");
+    }
+    syntax::TypeSpecifierNonArray::ISamplerCube => {
+      let _ = f.write_str("isamplerCube");
+    }
+    syntax::TypeSpecifierNonArray::IImageCube => {
+      let _ = f.write_str("iimageCube");
+    }
+    syntax::TypeSpecifierNonArray::ISampler2DRect => {
+      let _ = f.write_str("isampler2DRect");
+    }
+    syntax::TypeSpecifierNonArray::IImage2DRect => {
+      let _ = f.write_str("iimage2DRect");
+    }
+    syntax::TypeSpecifierNonArray::ISampler1DArray => {
+      let _ = f.write_str("isampler1DArray");
+    }
+    syntax::TypeSpecifierNonArray::IImage1DArray => {
+      let _ = f.write_str("iimage1DArray");
+    }
+    syntax::TypeSpecifierNonArray::ISampler2DArray => {
+      let _ = f.write_str("isampler2DArray");
+    }
+    syntax::TypeSpecifierNonArray::IImage2DArray => {
+      let _ = f.write_str("iimage2DArray");
+    }
+    syntax::TypeSpecifierNonArray::ISamplerBuffer => {
+      let _ = f.write_str("isamplerBuffer");
+    }
+    syntax::TypeSpecifierNonArray::IImageBuffer => {
+      let _ = f.write_str("iimageBuffer");
+    }
+    syntax::TypeSpecifierNonArray::ISampler2DMS => {
+      let _ = f.write_str("isampler2MS");
+    }
+    syntax::TypeSpecifierNonArray::IImage2DMS => {
+      let _ = f.write_str("iimage2DMS");
+    }
+    syntax::TypeSpecifierNonArray::ISampler2DMSArray => {
+      let _ = f.write_str("isampler2DMSArray");
+    }
+    syntax::TypeSpecifierNonArray::IImage2DMSArray => {
+      let _ = f.write_str("iimage2DMSArray");
+    }
+    syntax::TypeSpecifierNonArray::ISamplerCubeArray => {
+      let _ = f.write_str("isamplerCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::IImageCubeArray => {
+      let _ = f.write_str("iimageCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::AtomicUInt => {
+      let _ = f.write_str("atomic_uint");
+    }
+    syntax::TypeSpecifierNonArray::USampler1D => {
+      let _ = f.write_str("usampler1D");
+    }
+    syntax::TypeSpecifierNonArray::UImage1D => {
+      let _ = f.write_str("uimage1D");
+    }
+    syntax::TypeSpecifierNonArray::USampler2D => {
+      let _ = f.write_str("usampler2D");
+    }
+    syntax::TypeSpecifierNonArray::UImage2D => {
+      let _ = f.write_str("uimage2D");
+    }
+    syntax::TypeSpecifierNonArray::USampler3D => {
+      let _ = f.write_str("usampler3D");
+    }
+    syntax::TypeSpecifierNonArray::UImage3D => {
+      let _ = f.write_str("uimage3D");
+    }
+    syntax::TypeSpecifierNonArray::USamplerCube => {
+      let _ = f.write_str("usamplerCube");
+    }
+    syntax::TypeSpecifierNonArray::UImageCube => {
+      let _ = f.write_str("uimageCube");
+    }
+    syntax::TypeSpecifierNonArray::USampler2DRect => {
+      let _ = f.write_str("usampler2DRect");
+    }
+    syntax::TypeSpecifierNonArray::UImage2DRect => {
+      let _ = f.write_str("uimage2DRect");
+    }
+    syntax::TypeSpecifierNonArray::USampler1DArray => {
+      let _ = f.write_str("usampler1DArray");
+    }
+    syntax::TypeSpecifierNonArray::UImage1DArray => {
+      let _ = f.write_str("uimage1DArray");
+    }
+    syntax::TypeSpecifierNonArray::USampler2DArray => {
+      let _ = f.write_str("usampler2DArray");
+    }
+    syntax::TypeSpecifierNonArray::UImage2DArray => {
+      let _ = f.write_str("uimage2DArray");
+    }
+    syntax::TypeSpecifierNonArray::USamplerBuffer => {
+      let _ = f.write_str("usamplerBuffer");
+    }
+    syntax::TypeSpecifierNonArray::UImageBuffer => {
+      let _ = f.write_str("uimageBuffer");
+    }
+    syntax::TypeSpecifierNonArray::USampler2DMS => {
+      let _ = f.write_str("usampler2DMS");
+    }
+    syntax::TypeSpecifierNonArray::UImage2DMS => {
+      let _ = f.write_str("uimage2DMS");
+    }
+    syntax::TypeSpecifierNonArray::USampler2DMSArray => {
+      let _ = f.write_str("usamplerDMSArray");
+    }
+    syntax::TypeSpecifierNonArray::UImage2DMSArray => {
+      let _ = f.write_str("uimage2DMSArray");
+    }
+    syntax::TypeSpecifierNonArray::USamplerCubeArray => {
+      let _ = f.write_str("usamplerCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::UImageCubeArray => {
+      let _ = f.write_str("uimageCubeArray");
+    }
+    syntax::TypeSpecifierNonArray::Struct(ref s) => show_struct_non_declaration(f, s),
+    syntax::TypeSpecifierNonArray::TypeName(ref tn) => show_type_name(f, tn),
+  }
+}
+
+pub fn show_type_specifier<F>(f: &mut F, t: &syntax::TypeSpecifier)
+where
+  F: Write,
+{
+  show_type_specifier_non_array(f, &t.ty);
+
+  if let Some(ref arr_spec) = t.array_specifier {
+    show_array_spec(f, arr_spec);
+  }
+}
+
+pub fn show_fully_specified_type<F>(f: &mut F, t: &syntax::FullySpecifiedType)
+where
+  F: Write,
+{
+  if let Some(ref qual) = t.qualifier {
+    show_type_qualifier(f, &qual);
+    let _ = f.write_str(" ");
+  }
+
+  show_type_specifier(f, &t.ty);
+}
+
+pub fn show_struct_non_declaration<F>(f: &mut F, s: &syntax::StructSpecifier)
+where
+  F: Write,
+{
+  let _ = f.write_str("struct ");
+
+  if let Some(ref name) = s.name {
+    let _ = write!(f, "{} ", name);
+  }
+
+  let _ = f.write_str("{\n");
+
+  for field in &s.fields.0 {
+    show_struct_field(f, field);
+  }
+
+  let _ = f.write_str("}");
+}
+
+pub fn show_struct<F>(f: &mut F, s: &syntax::StructSpecifier)
+where
+  F: Write,
+{
+  show_struct_non_declaration(f, s);
+  let _ = f.write_str(";\n");
+}
+
+pub fn show_struct_field<F>(f: &mut F, field: &syntax::StructFieldSpecifier)
+where
+  F: Write,
+{
+  if let Some(ref qual) = field.qualifier {
+    show_type_qualifier(f, &qual);
+    let _ = f.write_str(" ");
+  }
+
+  show_type_specifier(f, &field.ty);
+  let _ = f.write_str(" ");
+
+  // there’s at least one identifier
+  let mut identifiers = field.identifiers.0.iter();
+  let identifier = identifiers.next().unwrap();
+
+  show_arrayed_identifier(f, identifier);
+
+  // write the rest of the identifiers
+  for identifier in identifiers {
+    let _ = f.write_str(", ");
+    show_arrayed_identifier(f, identifier);
+  }
+
+  let _ = f.write_str(";\n");
+}
+
+pub fn show_array_spec<F>(f: &mut F, a: &syntax::ArraySpecifier)
+where
+  F: Write,
+{
+  match *a {
+    syntax::ArraySpecifier::Unsized => {
+      let _ = f.write_str("[]");
+    }
+    syntax::ArraySpecifier::ExplicitlySized(ref e) => {
+      let _ = f.write_str("[");
+      show_expr(f, &e);
+      let _ = f.write_str("]");
+    }
+  }
+}
+
+pub fn show_arrayed_identifier<F>(f: &mut F, a: &syntax::ArrayedIdentifier)
+where
+  F: Write,
+{
+  let _ = write!(f, "{}", a.ident);
+
+  if let Some(ref arr_spec) = a.array_spec {
+    show_array_spec(f, arr_spec);
+  }
+}
+
+pub fn show_type_qualifier<F>(f: &mut F, q: &syntax::TypeQualifier)
+where
+  F: Write,
+{
+  let mut qualifiers = q.qualifiers.0.iter();
+  let first = qualifiers.next().unwrap();
+
+  show_type_qualifier_spec(f, first);
+
+  for qual_spec in qualifiers {
+    let _ = f.write_str(" ");
+    show_type_qualifier_spec(f, qual_spec)
+  }
+}
+
+pub fn show_type_qualifier_spec<F>(f: &mut F, q: &syntax::TypeQualifierSpec)
+where
+  F: Write,
+{
+  match *q {
+    syntax::TypeQualifierSpec::Storage(ref s) => show_storage_qualifier(f, &s),
+    syntax::TypeQualifierSpec::Layout(ref l) => show_layout_qualifier(f, &l),
+    syntax::TypeQualifierSpec::Precision(ref p) => show_precision_qualifier(f, &p),
+    syntax::TypeQualifierSpec::Interpolation(ref i) => show_interpolation_qualifier(f, &i),
+    syntax::TypeQualifierSpec::Invariant => {
+      let _ = f.write_str("invariant");
+    }
+    syntax::TypeQualifierSpec::Precise => {
+      let _ = f.write_str("precise");
+    }
+  }
+}
+
+pub fn show_storage_qualifier<F>(f: &mut F, q: &syntax::StorageQualifier)
+where
+  F: Write,
+{
+  match *q {
+    syntax::StorageQualifier::Const => {
+      let _ = f.write_str("const");
+    }
+    syntax::StorageQualifier::InOut => {
+      let _ = f.write_str("inout");
+    }
+    syntax::StorageQualifier::In => {
+      let _ = f.write_str("in");
+    }
+    syntax::StorageQualifier::Out => {
+      let _ = f.write_str("out");
+    }
+    syntax::StorageQualifier::Centroid => {
+      let _ = f.write_str("centroid");
+    }
+    syntax::StorageQualifier::Patch => {
+      let _ = f.write_str("patch");
+    }
+    syntax::StorageQualifier::Sample => {
+      let _ = f.write_str("sample");
+    }
+    syntax::StorageQualifier::Uniform => {
+      let _ = f.write_str("uniform");
+    }
+    syntax::StorageQualifier::Attribute => {
+      let _ = f.write_str("attribute");
+    }
+    syntax::StorageQualifier::Varying => {
+      let _ = f.write_str("varying");
+    }
+    syntax::StorageQualifier::Buffer => {
+      let _ = f.write_str("buffer");
+    }
+    syntax::StorageQualifier::Shared => {
+      let _ = f.write_str("shared");
+    }
+    syntax::StorageQualifier::Coherent => {
+      let _ = f.write_str("coherent");
+    }
+    syntax::StorageQualifier::Volatile => {
+      let _ = f.write_str("volatile");
+    }
+    syntax::StorageQualifier::Restrict => {
+      let _ = f.write_str("restrict");
+    }
+    syntax::StorageQualifier::ReadOnly => {
+      let _ = f.write_str("readonly");
+    }
+    syntax::StorageQualifier::WriteOnly => {
+      let _ = f.write_str("writeonly");
+    }
+    syntax::StorageQualifier::Subroutine(ref n) => show_subroutine(f, &n),
+  }
+}
+
+pub fn show_subroutine<F>(f: &mut F, types: &Vec<syntax::TypeName>)
+where
+  F: Write,
+{
+  let _ = f.write_str("subroutine");
+
+  if !types.is_empty() {
+    let _ = f.write_str("(");
+
+    let mut types_iter = types.iter();
+    let first = types_iter.next().unwrap();
+
+    show_type_name(f, first);
+
+    for type_name in types_iter {
+      let _ = f.write_str(", ");
+      show_type_name(f, type_name);
+    }
+
+    let _ = f.write_str(")");
+  }
+}
+
+pub fn show_layout_qualifier<F>(f: &mut F, l: &syntax::LayoutQualifier)
+where
+  F: Write,
+{
+  let mut qualifiers = l.ids.0.iter();
+  let first = qualifiers.next().unwrap();
+
+  let _ = f.write_str("layout (");
+  show_layout_qualifier_spec(f, first);
+
+  for qual_spec in qualifiers {
+    let _ = f.write_str(", ");
+    show_layout_qualifier_spec(f, qual_spec);
+  }
+
+  let _ = f.write_str(")");
+}
+
+pub fn show_layout_qualifier_spec<F>(f: &mut F, l: &syntax::LayoutQualifierSpec)
+where
+  F: Write,
+{
+  match *l {
+    syntax::LayoutQualifierSpec::Identifier(ref i, Some(ref e)) => {
+      let _ = write!(f, "{} = ", i);
+      show_expr(f, &e);
+    }
+    syntax::LayoutQualifierSpec::Identifier(ref i, None) => show_identifier(f, &i),
+    syntax::LayoutQualifierSpec::Shared => {
+      let _ = f.write_str("shared");
+    }
+  }
+}
+
+pub fn show_precision_qualifier<F>(f: &mut F, p: &syntax::PrecisionQualifier)
+where
+  F: Write,
+{
+  match *p {
+    syntax::PrecisionQualifier::High => {
+      let _ = f.write_str("highp");
+    }
+    syntax::PrecisionQualifier::Medium => {
+      let _ = f.write_str("mediump");
+    }
+    syntax::PrecisionQualifier::Low => {
+      let _ = f.write_str("low");
+    }
+  }
+}
+
+pub fn show_interpolation_qualifier<F>(f: &mut F, i: &syntax::InterpolationQualifier)
+where
+  F: Write,
+{
+  match *i {
+    syntax::InterpolationQualifier::Smooth => {
+      let _ = f.write_str("smooth");
+    }
+    syntax::InterpolationQualifier::Flat => {
+      let _ = f.write_str("flat");
+    }
+    syntax::InterpolationQualifier::NoPerspective => {
+      let _ = f.write_str("noperspective");
+    }
+  }
+}
+
+pub fn show_float<F>(f: &mut F, x: f32)
+where
+  F: Write,
+{
+  if x.fract() == 0. {
+    let _ = write!(f, "{}.", x);
+  } else {
+    let _ = write!(f, "{}", x);
+  }
+}
+
+pub fn show_double<F>(f: &mut F, x: f64)
+where
+  F: Write,
+{
+  if x.fract() == 0. {
+    let _ = write!(f, "{}.", x);
+  } else {
+    let _ = write!(f, "{}", x);
+  }
+}
+
+pub fn show_expr<F>(f: &mut F, expr: &syntax::Expr)
+where
+  F: Write,
+{
+  match *expr {
+    syntax::Expr::Variable(ref i) => show_identifier(f, &i),
+    syntax::Expr::IntConst(ref x) => {
+      let _ = write!(f, "{}", x);
+    }
+    syntax::Expr::UIntConst(ref x) => {
+      let _ = write!(f, "{}u", x);
+    }
+    syntax::Expr::BoolConst(ref x) => {
+      let _ = write!(f, "{}", x);
+    }
+    syntax::Expr::FloatConst(ref x) => show_float(f, *x),
+    syntax::Expr::DoubleConst(ref x) => show_double(f, *x),
+    syntax::Expr::Unary(ref op, ref e) => {
+      show_unary_op(f, &op);
+      let _ = f.write_str("(");
+      show_expr(f, &e);
+      let _ = f.write_str(")");
+    }
+    syntax::Expr::Binary(ref op, ref l, ref r) => {
+      let _ = f.write_str("(");
+      show_expr(f, &l);
+      let _ = f.write_str(")");
+      show_binary_op(f, &op);
+      let _ = f.write_str("(");
+      show_expr(f, &r);
+      let _ = f.write_str(")");
+    }
+    syntax::Expr::Ternary(ref c, ref s, ref e) => {
+      show_expr(f, &c);
+      let _ = f.write_str(" ? ");
+      show_expr(f, &s);
+      let _ = f.write_str(" : ");
+      show_expr(f, &e);
+    }
+    syntax::Expr::Assignment(ref v, ref op, ref e) => {
+      show_expr(f, &v);
+      let _ = f.write_str(" ");
+      show_assignment_op(f, &op);
+      let _ = f.write_str(" ");
+      show_expr(f, &e);
+    }
+    syntax::Expr::Bracket(ref e, ref a) => {
+      show_expr(f, &e);
+      show_array_spec(f, &a);
+    }
+    syntax::Expr::FunCall(ref fun, ref args) => {
+      show_function_identifier(f, &fun);
+      let _ = f.write_str("(");
+
+      if !args.is_empty() {
+        let mut args_iter = args.iter();
+        let first = args_iter.next().unwrap();
+        show_expr(f, first);
+
+        for e in args_iter {
+          let _ = f.write_str(", ");
+          show_expr(f, e);
+        }
+      }
+
+      let _ = f.write_str(")");
+    }
+    syntax::Expr::Dot(ref e, ref i) => {
+      let _ = f.write_str("(");
+      show_expr(f, &e);
+      let _ = f.write_str(")");
+      let _ = f.write_str(".");
+      show_identifier(f, &i);
+    }
+    syntax::Expr::PostInc(ref e) => {
+      show_expr(f, &e);
+      let _ = f.write_str("++");
+    }
+    syntax::Expr::PostDec(ref e) => {
+      show_expr(f, &e);
+      let _ = f.write_str("--");
+    }
+    syntax::Expr::Comma(ref a, ref b) => {
+      show_expr(f, &a);
+      let _ = f.write_str(", ");
+      show_expr(f, &b);
+    }
+  }
+}
+
+pub fn show_path<F>(f: &mut F, path: &syntax::Path)
+where
+  F: Write,
+{
+  match path {
+    syntax::Path::Absolute(s) => {
+      let _ = write!(f, "<{}>", s);
+    }
+    syntax::Path::Relative(s) => {
+      let _ = write!(f, "\"{}\"", s);
+    }
+  }
+}
+
+pub fn show_unary_op<F>(f: &mut F, op: &syntax::UnaryOp)
+where
+  F: Write,
+{
+  match *op {
+    syntax::UnaryOp::Inc => {
+      let _ = f.write_str("++");
+    }
+    syntax::UnaryOp::Dec => {
+      let _ = f.write_str("--");
+    }
+    syntax::UnaryOp::Add => {
+      let _ = f.write_str("+");
+    }
+    syntax::UnaryOp::Minus => {
+      let _ = f.write_str("-");
+    }
+    syntax::UnaryOp::Not => {
+      let _ = f.write_str("!");
+    }
+    syntax::UnaryOp::Complement => {
+      let _ = f.write_str("~");
+    }
+  }
+}
+
+pub fn show_binary_op<F>(f: &mut F, op: &syntax::BinaryOp)
+where
+  F: Write,
+{
+  match *op {
+    syntax::BinaryOp::Or => {
+      let _ = f.write_str("||");
+    }
+    syntax::BinaryOp::Xor => {
+      let _ = f.write_str("^^");
+    }
+    syntax::BinaryOp::And => {
+      let _ = f.write_str("&&");
+    }
+    syntax::BinaryOp::BitOr => {
+      let _ = f.write_str("|");
+    }
+    syntax::BinaryOp::BitXor => {
+      let _ = f.write_str("^");
+    }
+    syntax::BinaryOp::BitAnd => {
+      let _ = f.write_str("&");
+    }
+    syntax::BinaryOp::Equal => {
+      let _ = f.write_str("==");
+    }
+    syntax::BinaryOp::NonEqual => {
+      let _ = f.write_str("!=");
+    }
+    syntax::BinaryOp::LT => {
+      let _ = f.write_str("<");
+    }
+    syntax::BinaryOp::GT => {
+      let _ = f.write_str(">");
+    }
+    syntax::BinaryOp::LTE => {
+      let _ = f.write_str("<=");
+    }
+    syntax::BinaryOp::GTE => {
+      let _ = f.write_str(">=");
+    }
+    syntax::BinaryOp::LShift => {
+      let _ = f.write_str("<<");
+    }
+    syntax::BinaryOp::RShift => {
+      let _ = f.write_str(">>");
+    }
+    syntax::BinaryOp::Add => {
+      let _ = f.write_str("+");
+    }
+    syntax::BinaryOp::Sub => {
+      let _ = f.write_str("-");
+    }
+    syntax::BinaryOp::Mult => {
+      let _ = f.write_str("*");
+    }
+    syntax::BinaryOp::Div => {
+      let _ = f.write_str("/");
+    }
+    syntax::BinaryOp::Mod => {
+      let _ = f.write_str("%");
+    }
+  }
+}
+
+pub fn show_assignment_op<F>(f: &mut F, op: &syntax::AssignmentOp)
+where
+  F: Write,
+{
+  match *op {
+    syntax::AssignmentOp::Equal => {
+      let _ = f.write_str("=");
+    }
+    syntax::AssignmentOp::Mult => {
+      let _ = f.write_str("*=");
+    }
+    syntax::AssignmentOp::Div => {
+      let _ = f.write_str("/=");
+    }
+    syntax::AssignmentOp::Mod => {
+      let _ = f.write_str("%=");
+    }
+    syntax::AssignmentOp::Add => {
+      let _ = f.write_str("+=");
+    }
+    syntax::AssignmentOp::Sub => {
+      let _ = f.write_str("-=");
+    }
+    syntax::AssignmentOp::LShift => {
+      let _ = f.write_str("<<=");
+    }
+    syntax::AssignmentOp::RShift => {
+      let _ = f.write_str(">>=");
+    }
+    syntax::AssignmentOp::And => {
+      let _ = f.write_str("&=");
+    }
+    syntax::AssignmentOp::Xor => {
+      let _ = f.write_str("^=");
+    }
+    syntax::AssignmentOp::Or => {
+      let _ = f.write_str("|=");
+    }
+  }
+}
+
+pub fn show_function_identifier<F>(f: &mut F, i: &syntax::FunIdentifier)
+where
+  F: Write,
+{
+  match *i {
+    syntax::FunIdentifier::Identifier(ref n) => show_identifier(f, &n),
+    syntax::FunIdentifier::Expr(ref e) => show_expr(f, &*e),
+  }
+}
+
+pub fn show_declaration<F>(f: &mut F, d: &syntax::Declaration)
+where
+  F: Write,
+{
+  match *d {
+    syntax::Declaration::FunctionPrototype(ref proto) => {
+      show_function_prototype(f, &proto);
+      let _ = f.write_str(";\n");
+    }
+    syntax::Declaration::InitDeclaratorList(ref list) => {
+      show_init_declarator_list(f, &list);
+      let _ = f.write_str(";\n");
+    }
+    syntax::Declaration::Precision(ref qual, ref ty) => {
+      show_precision_qualifier(f, &qual);
+      show_type_specifier(f, &ty);
+      let _ = f.write_str(";\n");
+    }
+    syntax::Declaration::Block(ref block) => {
+      show_block(f, &block);
+      let _ = f.write_str(";\n");
+    }
+    syntax::Declaration::Global(ref qual, ref identifiers) => {
+      show_type_qualifier(f, &qual);
+
+      if !identifiers.is_empty() {
+        let mut iter = identifiers.iter();
+        let first = iter.next().unwrap();
+        show_identifier(f, first);
+
+        for identifier in iter {
+          let _ = write!(f, ", {}", identifier);
+        }
+      }
+
+      let _ = f.write_str(";\n");
+    }
+  }
+}
+
+pub fn show_function_prototype<F>(f: &mut F, fp: &syntax::FunctionPrototype)
+where
+  F: Write,
+{
+  show_fully_specified_type(f, &fp.ty);
+  let _ = f.write_str(" ");
+  show_identifier(f, &fp.name);
+
+  let _ = f.write_str("(");
+
+  if !fp.parameters.is_empty() {
+    let mut iter = fp.parameters.iter();
+    let first = iter.next().unwrap();
+    show_function_parameter_declaration(f, first);
+
+    for param in iter {
+      let _ = f.write_str(", ");
+      show_function_parameter_declaration(f, param);
+    }
+  }
+
+  let _ = f.write_str(")");
+}
+pub fn show_function_parameter_declaration<F>(f: &mut F, p: &syntax::FunctionParameterDeclaration)
+where
+  F: Write,
+{
+  match *p {
+    syntax::FunctionParameterDeclaration::Named(ref qual, ref fpd) => {
+      if let Some(ref q) = *qual {
+        show_type_qualifier(f, q);
+        let _ = f.write_str(" ");
+      }
+
+      show_function_parameter_declarator(f, fpd);
+    }
+    syntax::FunctionParameterDeclaration::Unnamed(ref qual, ref ty) => {
+      if let Some(ref q) = *qual {
+        show_type_qualifier(f, q);
+        let _ = f.write_str(" ");
+      }
+
+      show_type_specifier(f, ty);
+    }
+  }
+}
+
+pub fn show_function_parameter_declarator<F>(f: &mut F, p: &syntax::FunctionParameterDeclarator)
+where
+  F: Write,
+{
+  show_type_specifier(f, &p.ty);
+  let _ = f.write_str(" ");
+  show_arrayed_identifier(f, &p.ident);
+}
+
+pub fn show_init_declarator_list<F>(f: &mut F, i: &syntax::InitDeclaratorList)
+where
+  F: Write,
+{
+  show_single_declaration(f, &i.head);
+
+  for decl in &i.tail {
+    let _ = f.write_str(", ");
+    show_single_declaration_no_type(f, decl);
+  }
+}
+
+pub fn show_single_declaration<F>(f: &mut F, d: &syntax::SingleDeclaration)
+where
+  F: Write,
+{
+  show_fully_specified_type(f, &d.ty);
+
+  if let Some(ref name) = d.name {
+    let _ = f.write_str(" ");
+    show_identifier(f, name);
+  }
+
+  if let Some(ref arr_spec) = d.array_specifier {
+    show_array_spec(f, arr_spec);
+  }
+
+  if let Some(ref initializer) = d.initializer {
+    let _ = f.write_str(" = ");
+    show_initializer(f, initializer);
+  }
+}
+
+pub fn show_single_declaration_no_type<F>(f: &mut F, d: &syntax::SingleDeclarationNoType)
+where
+  F: Write,
+{
+  show_arrayed_identifier(f, &d.ident);
+
+  if let Some(ref initializer) = d.initializer {
+    let _ = f.write_str(" = ");
+    show_initializer(f, initializer);
+  }
+}
+
+pub fn show_initializer<F>(f: &mut F, i: &syntax::Initializer)
+where
+  F: Write,
+{
+  match *i {
+    syntax::Initializer::Simple(ref e) => show_expr(f, e),
+    syntax::Initializer::List(ref list) => {
+      let mut iter = list.0.iter();
+      let first = iter.next().unwrap();
+
+      let _ = f.write_str("{ ");
+      show_initializer(f, first);
+
+      for ini in iter {
+        let _ = f.write_str(", ");
+        show_initializer(f, ini);
+      }
+
+      let _ = f.write_str(" }");
+    }
+  }
+}
+
+pub fn show_block<F>(f: &mut F, b: &syntax::Block)
+where
+  F: Write,
+{
+  show_type_qualifier(f, &b.qualifier);
+  let _ = f.write_str(" ");
+  show_identifier(f, &b.name);
+  let _ = f.write_str(" {");
+
+  for field in &b.fields {
+    show_struct_field(f, field);
+    let _ = f.write_str("\n");
+  }
+  let _ = f.write_str("}");
+
+  if let Some(ref ident) = b.identifier {
+    show_arrayed_identifier(f, ident);
+  }
+}
+
+pub fn show_function_definition<F>(f: &mut F, fd: &syntax::FunctionDefinition)
+where
+  F: Write,
+{
+  show_function_prototype(f, &fd.prototype);
+  let _ = f.write_str(" ");
+  show_compound_statement(f, &fd.statement);
+}
+
+pub fn show_compound_statement<F>(f: &mut F, cst: &syntax::CompoundStatement)
+where
+  F: Write,
+{
+  let _ = f.write_str("{\n");
+
+  for st in &cst.statement_list {
+    show_statement(f, st);
+  }
+
+  let _ = f.write_str("}\n");
+}
+
+pub fn show_statement<F>(f: &mut F, st: &syntax::Statement)
+where
+  F: Write,
+{
+  match *st {
+    syntax::Statement::Compound(ref cst) => show_compound_statement(f, cst),
+    syntax::Statement::Simple(ref sst) => show_simple_statement(f, sst),
+  }
+}
+
+pub fn show_simple_statement<F>(f: &mut F, sst: &syntax::SimpleStatement)
+where
+  F: Write,
+{
+  match *sst {
+    syntax::SimpleStatement::Declaration(ref d) => show_declaration(f, d),
+    syntax::SimpleStatement::Expression(ref e) => show_expression_statement(f, e),
+    syntax::SimpleStatement::Selection(ref s) => show_selection_statement(f, s),
+    syntax::SimpleStatement::Switch(ref s) => show_switch_statement(f, s),
+    syntax::SimpleStatement::CaseLabel(ref cl) => show_case_label(f, cl),
+    syntax::SimpleStatement::Iteration(ref i) => show_iteration_statement(f, i),
+    syntax::SimpleStatement::Jump(ref j) => show_jump_statement(f, j),
+  }
+}
+
+pub fn show_expression_statement<F>(f: &mut F, est: &syntax::ExprStatement)
+where
+  F: Write,
+{
+  if let Some(ref e) = *est {
+    show_expr(f, e);
+  }
+
+  let _ = f.write_str(";\n");
+}
+
+pub fn show_selection_statement<F>(f: &mut F, sst: &syntax::SelectionStatement)
+where
+  F: Write,
+{
+  let _ = f.write_str("if (");
+  show_expr(f, &sst.cond);
+  let _ = f.write_str(") {\n");
+  show_selection_rest_statement(f, &sst.rest);
+}
+
+pub fn show_selection_rest_statement<F>(f: &mut F, sst: &syntax::SelectionRestStatement)
+where
+  F: Write,
+{
+  match *sst {
+    syntax::SelectionRestStatement::Statement(ref if_st) => {
+      show_statement(f, if_st);
+      let _ = f.write_str("}\n");
+    }
+    syntax::SelectionRestStatement::Else(ref if_st, ref else_st) => {
+      show_statement(f, if_st);
+      let _ = f.write_str("} else ");
+      show_statement(f, else_st);
+    }
+  }
+}
+
+pub fn show_switch_statement<F>(f: &mut F, sst: &syntax::SwitchStatement)
+where
+  F: Write,
+{
+  let _ = f.write_str("switch (");
+  show_expr(f, &sst.head);
+  let _ = f.write_str(") {\n");
+
+  for st in &sst.body {
+    show_statement(f, st);
+  }
+
+  let _ = f.write_str("}\n");
+}
+
+pub fn show_case_label<F>(f: &mut F, cl: &syntax::CaseLabel)
+where
+  F: Write,
+{
+  match *cl {
+    syntax::CaseLabel::Case(ref e) => {
+      let _ = f.write_str("case ");
+      show_expr(f, e);
+      let _ = f.write_str(":\n");
+    }
+    syntax::CaseLabel::Def => {
+      let _ = f.write_str("default:\n");
+    }
+  }
+}
+
+pub fn show_iteration_statement<F>(f: &mut F, ist: &syntax::IterationStatement)
+where
+  F: Write,
+{
+  match *ist {
+    syntax::IterationStatement::While(ref cond, ref body) => {
+      let _ = f.write_str("while (");
+      show_condition(f, cond);
+      let _ = f.write_str(") ");
+      show_statement(f, body);
+    }
+    syntax::IterationStatement::DoWhile(ref body, ref cond) => {
+      let _ = f.write_str("do ");
+      show_statement(f, body);
+      let _ = f.write_str(" while (");
+      show_expr(f, cond);
+      let _ = f.write_str(")\n");
+    }
+    syntax::IterationStatement::For(ref init, ref rest, ref body) => {
+      let _ = f.write_str("for (");
+      show_for_init_statement(f, init);
+      show_for_rest_statement(f, rest);
+      let _ = f.write_str(") ");
+      show_statement(f, body);
+    }
+  }
+}
+
+pub fn show_condition<F>(f: &mut F, c: &syntax::Condition)
+where
+  F: Write,
+{
+  match *c {
+    syntax::Condition::Expr(ref e) => show_expr(f, e),
+    syntax::Condition::Assignment(ref ty, ref name, ref initializer) => {
+      show_fully_specified_type(f, ty);
+      let _ = f.write_str(" ");
+      show_identifier(f, name);
+      let _ = f.write_str(" = ");
+      show_initializer(f, initializer);
+    }
+  }
+}
+
+pub fn show_for_init_statement<F>(f: &mut F, i: &syntax::ForInitStatement)
+where
+  F: Write,
+{
+  match *i {
+    syntax::ForInitStatement::Expression(ref expr) => {
+      if let Some(ref e) = *expr {
+        show_expr(f, e);
+      }
+    }
+    syntax::ForInitStatement::Declaration(ref d) => show_declaration(f, d),
+  }
+}
+
+pub fn show_for_rest_statement<F>(f: &mut F, r: &syntax::ForRestStatement)
+where
+  F: Write,
+{
+  if let Some(ref cond) = r.condition {
+    show_condition(f, cond);
+  }
+
+  let _ = f.write_str("; ");
+
+  if let Some(ref e) = r.post_expr {
+    show_expr(f, e);
+  }
+}
+
+pub fn show_jump_statement<F>(f: &mut F, j: &syntax::JumpStatement)
+where
+  F: Write,
+{
+  match *j {
+    syntax::JumpStatement::Continue => {
+      let _ = f.write_str("continue;\n");
+    }
+    syntax::JumpStatement::Break => {
+      let _ = f.write_str("break;\n");
+    }
+    syntax::JumpStatement::Discard => {
+      let _ = f.write_str("discard;\n");
+    }
+    syntax::JumpStatement::Return(ref e) => {
+      let _ = f.write_str("return ");
+      if let Some(e) = e {
+        show_expr(f, e);
+      }
+      let _ = f.write_str(";\n");
+    }
+  }
+}
+
+pub fn show_preprocessor<F>(f: &mut F, pp: &syntax::Preprocessor)
+where
+  F: Write,
+{
+  match *pp {
+    syntax::Preprocessor::Define(ref pd) => show_preprocessor_define(f, pd),
+    syntax::Preprocessor::Else => show_preprocessor_else(f),
+    syntax::Preprocessor::ElseIf(ref pei) => show_preprocessor_elseif(f, pei),
+    syntax::Preprocessor::EndIf => show_preprocessor_endif(f),
+    syntax::Preprocessor::Error(ref pe) => show_preprocessor_error(f, pe),
+    syntax::Preprocessor::If(ref pi) => show_preprocessor_if(f, pi),
+    syntax::Preprocessor::IfDef(ref pid) => show_preprocessor_ifdef(f, pid),
+    syntax::Preprocessor::IfNDef(ref pind) => show_preprocessor_ifndef(f, pind),
+    syntax::Preprocessor::Include(ref pi) => show_preprocessor_include(f, pi),
+    syntax::Preprocessor::Line(ref pl) => show_preprocessor_line(f, pl),
+    syntax::Preprocessor::Pragma(ref pp) => show_preprocessor_pragma(f, pp),
+    syntax::Preprocessor::Undef(ref pu) => show_preprocessor_undef(f, pu),
+    syntax::Preprocessor::Version(ref pv) => show_preprocessor_version(f, pv),
+    syntax::Preprocessor::Extension(ref pe) => show_preprocessor_extension(f, pe),
+  }
+}
+
+pub fn show_preprocessor_define<F>(f: &mut F, pd: &syntax::PreprocessorDefine)
+where
+  F: Write,
+{
+  match *pd {
+    syntax::PreprocessorDefine::ObjectLike {
+      ref ident,
+      ref value,
+    } => {
+      let _ = write!(f, "#define {} {}\n", ident, value);
+    }
+
+    syntax::PreprocessorDefine::FunctionLike {
+      ref ident,
+      ref args,
+      ref value,
+    } => {
+      let _ = write!(f, "#define {}(", ident);
+
+      if !args.is_empty() {
+        let _ = write!(f, "{}", &args[0]);
+
+        for arg in &args[1..args.len()] {
+          let _ = write!(f, ", {}", arg);
+        }
+      }
+
+      let _ = write!(f, ") {}\n", value);
+    }
+  }
+}
+
+pub fn show_preprocessor_else<F>(f: &mut F)
+where
+  F: Write,
+{
+  let _ = f.write_str("#else\n");
+}
+
+pub fn show_preprocessor_elseif<F>(f: &mut F, pei: &syntax::PreprocessorElseIf)
+where
+  F: Write,
+{
+  let _ = write!(f, "#elseif {}\n", pei.condition);
+}
+
+pub fn show_preprocessor_error<F>(f: &mut F, pe: &syntax::PreprocessorError)
+where
+  F: Write,
+{
+  let _ = writeln!(f, "#error {}", pe.message);
+}
+
+pub fn show_preprocessor_endif<F>(f: &mut F)
+where
+  F: Write,
+{
+  let _ = f.write_str("#endif\n");
+}
+
+pub fn show_preprocessor_if<F>(f: &mut F, pi: &syntax::PreprocessorIf)
+where
+  F: Write,
+{
+  let _ = write!(f, "#if {}\n", pi.condition);
+}
+
+pub fn show_preprocessor_ifdef<F>(f: &mut F, pid: &syntax::PreprocessorIfDef)
+where
+  F: Write,
+{
+  let _ = f.write_str("#ifdef ");
+  show_identifier(f, &pid.ident);
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_ifndef<F>(f: &mut F, pind: &syntax::PreprocessorIfNDef)
+where
+  F: Write,
+{
+  let _ = f.write_str("#ifndef ");
+  show_identifier(f, &pind.ident);
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_include<F>(f: &mut F, pi: &syntax::PreprocessorInclude)
+where
+  F: Write,
+{
+  let _ = f.write_str("#include ");
+  show_path(f, &pi.path);
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_line<F>(f: &mut F, pl: &syntax::PreprocessorLine)
+where
+  F: Write,
+{
+  let _ = write!(f, "#line {}", pl.line);
+  if let Some(source_string_number) = pl.source_string_number {
+    let _ = write!(f, " {}", source_string_number);
+  }
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_pragma<F>(f: &mut F, pp: &syntax::PreprocessorPragma)
+where
+  F: Write,
+{
+  let _ = writeln!(f, "#pragma {}", pp.command);
+}
+
+pub fn show_preprocessor_undef<F>(f: &mut F, pud: &syntax::PreprocessorUndef)
+where
+  F: Write,
+{
+  let _ = f.write_str("#undef ");
+  show_identifier(f, &pud.name);
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_version<F>(f: &mut F, pv: &syntax::PreprocessorVersion)
+where
+  F: Write,
+{
+  let _ = write!(f, "#version {}", pv.version);
+
+  if let Some(ref profile) = pv.profile {
+    match *profile {
+      syntax::PreprocessorVersionProfile::Core => {
+        let _ = f.write_str(" core");
+      }
+      syntax::PreprocessorVersionProfile::Compatibility => {
+        let _ = f.write_str(" compatibility");
+      }
+      syntax::PreprocessorVersionProfile::ES => {
+        let _ = f.write_str(" es");
+      }
+    }
+  }
+
+  let _ = f.write_str("\n");
+}
+
+pub fn show_preprocessor_extension<F>(f: &mut F, pe: &syntax::PreprocessorExtension)
+where
+  F: Write,
+{
+  let _ = f.write_str("#extension ");
+
+  match pe.name {
+    syntax::PreprocessorExtensionName::All => {
+      let _ = f.write_str("all");
+    }
+    syntax::PreprocessorExtensionName::Specific(ref n) => {
+      let _ = f.write_str(n);
+    }
+  }
+
+  if let Some(ref behavior) = pe.behavior {
+    match *behavior {
+      syntax::PreprocessorExtensionBehavior::Require => {
+        let _ = f.write_str(" : require");
+      }
+      syntax::PreprocessorExtensionBehavior::Enable => {
+        let _ = f.write_str(" : enable");
+      }
+      syntax::PreprocessorExtensionBehavior::Warn => {
+        let _ = f.write_str(" : warn");
+      }
+      syntax::PreprocessorExtensionBehavior::Disable => {
+        let _ = f.write_str(" : disable");
+      }
+    }
+  }
+
+  let _ = f.write_str("\n");
+}
+
+pub fn show_external_declaration<F>(f: &mut F, ed: &syntax::ExternalDeclaration)
+where
+  F: Write,
+{
+  match *ed {
+    syntax::ExternalDeclaration::Preprocessor(ref pp) => show_preprocessor(f, pp),
+    syntax::ExternalDeclaration::FunctionDefinition(ref fd) => show_function_definition(f, fd),
+    syntax::ExternalDeclaration::Declaration(ref d) => show_declaration(f, d),
+  }
+}
+
+pub fn show_translation_unit<F>(f: &mut F, tu: &syntax::TranslationUnit)
+where
+  F: Write,
+{
+  for ed in &(tu.0).0 {
+    show_external_declaration(f, ed);
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn roundtrip_glsl_complex_expr() {
+    use crate::parsers::expr;
+
+    let zero = syntax::Expr::DoubleConst(0.);
+    let ray = syntax::Expr::Variable("ray".into());
+    let raydir = syntax::Expr::Dot(Box::new(ray), "dir".into());
+    let vec4 = syntax::Expr::FunCall(
+      syntax::FunIdentifier::Identifier("vec4".into()),
+      vec![raydir, zero],
+    );
+    let view = syntax::Expr::Variable("view".into());
+    let iview = syntax::Expr::FunCall(
+      syntax::FunIdentifier::Identifier("inverse".into()),
+      vec![view],
+    );
+    let mul = syntax::Expr::Binary(syntax::BinaryOp::Mult, Box::new(iview), Box::new(vec4));
+    let xyz = syntax::Expr::Dot(Box::new(mul), "xyz".into());
+    let input = syntax::Expr::FunCall(
+      syntax::FunIdentifier::Identifier("normalize".into()),
+      vec![xyz],
+    );
+
+    let mut output = String::new();
+    show_expr(&mut output, &input);
+    let _ = output.write_str(";");
+
+    let back = expr(&output);
+
+    assert_eq!(back, Ok((";", input)), "intermediate source '{}'", output);
+  }
+}