Convert config fields header, trailer, after_includes to text fields.

src/bindgen/builder.rs

@@ -37,7 +37,7 @@ impl Builder {
 
     #[allow(unused)]
     pub fn with_header<S: AsRef<str>>(mut self, header: S) -> Builder {
-        self.config.header = Some(String::from(header.as_ref()));
+        self.config.header = String::from(header.as_ref()).into();
         self
     }
 
@@ -63,13 +63,13 @@ impl Builder {
 
     #[allow(unused)]
     pub fn with_after_include<S: AsRef<str>>(mut self, line: S) -> Builder {
-        self.config.after_includes = Some(String::from(line.as_ref()));
+        self.config.after_includes = String::from(line.as_ref()).into();
         self
     }
 
     #[allow(unused)]
     pub fn with_trailer<S: AsRef<str>>(mut self, trailer: S) -> Builder {
-        self.config.trailer = Some(String::from(trailer.as_ref()));
+        self.config.trailer = String::from(trailer.as_ref()).into();
         self
     }
 

src/bindgen/config.rs

@@ -894,22 +894,94 @@ pub struct CythonConfig {
     pub cimports: BTreeMap<String, Vec<String>>,
 }
 
+/// A line field can be a single line `field = "line"` or a struct `field = { language = "C", line = "struct" }`.
+#[derive(Debug, Clone, Deserialize)]
+#[serde(untagged)]
+pub enum Line {
+    AnyBackend(String),
+    WithBackend { language: Language, line: String },
+}
+impl Line {
+    pub fn line_for(&self, target: Language) -> Option<&str> {
+        match *self {
+            Line::AnyBackend(ref line) => Some(line.as_str()),
+            Line::WithBackend { language, ref line } if language == target => Some(line.as_str()),
+            _ => None,
+        }
+    }
+}
+impl From<String> for Line {
+    fn from(value: String) -> Self {
+        Self::AnyBackend(value)
+    }
+}
+
+/// A text field can be a line field or a sequence of lines or structs:
+/// ```toml
+/// field = [
+///    "sequence of lines",
+///    { language = "C", line = "or structs" },
+/// ]
+/// ```
+#[derive(Debug, Clone, Deserialize)]
+#[serde(untagged)]
+pub enum Text {
+    Line(Line),
+    Lines(Vec<Line>),
+}
+impl Text {
+    pub fn is_empty(&self) -> bool {
+        match *self {
+            Text::Line(_) => false,
+            Text::Lines(ref lines) => lines.is_empty(),
+        }
+    }
+    pub fn text_for(&self, target: Language) -> Vec<&str> {
+        let mut text = Vec::new();
+        match self {
+            Text::Line(line) => {
+                if let Some(s) = line.line_for(target) {
+                    text.push(s);
+                }
+            }
+            Text::Lines(lines) => {
+                for line in lines.iter() {
+                    if let Some(s) = line.line_for(target) {
+                        text.push(s);
+                    }
+                }
+            }
+        }
+        text
+    }
+}
+impl From<String> for Text {
+    fn from(value: String) -> Self {
+        Self::Line(value.into())
+    }
+}
+impl Default for Text {
+    fn default() -> Self {
+        Self::Lines(Vec::new())
+    }
+}
+
 /// A collection of settings to customize the generated bindings.
 #[derive(Debug, Clone, Deserialize)]
 #[serde(rename_all = "snake_case")]
 #[serde(deny_unknown_fields)]
 #[serde(default)]
 pub struct Config {
     /// Optional text to output at the beginning of the file
-    pub header: Option<String>,
+    pub header: Text,
     /// A list of additional includes to put at the beginning of the generated header
     pub includes: Vec<String>,
     /// A list of additional system includes to put at the beginning of the generated header
     pub sys_includes: Vec<String>,
     /// Optional verbatim code added after the include blocks
-    pub after_includes: Option<String>,
+    pub after_includes: Text,
     /// Optional text to output at the end of the file
-    pub trailer: Option<String>,
+    pub trailer: Text,
     /// Optional name to use for an include guard
     pub include_guard: Option<String>,
     /// Add a `#pragma once` guard
@@ -1032,11 +1104,11 @@ pub struct Config {
 impl Default for Config {
     fn default() -> Config {
         Config {
-            header: None,
+            header: Text::default(),
             includes: Vec::new(),
             sys_includes: Vec::new(),
-            after_includes: None,
-            trailer: None,
+            after_includes: Text::default(),
+            trailer: Text::default(),
             include_guard: None,
             pragma_once: false,
             autogen_warning: None,

src/bindgen/language_backend/clike.rs

@@ -344,9 +344,9 @@ impl LanguageBackend for CLikeLanguageBackend<'_> {
             write!(out, "/* Package version: {} */", package_version);
             out.new_line();
         }
-        if let Some(ref f) = self.config.header {
+        for line in self.config.header.text_for(self.config.language) {
             out.new_line_if_not_start();
-            write!(out, "{}", f);
+            write!(out, "{}", line);
             out.new_line();
         }
         if let Some(f) = self.config.include_guard() {
@@ -379,7 +379,7 @@ impl LanguageBackend for CLikeLanguageBackend<'_> {
         if self.config.no_includes
             && self.config.sys_includes().is_empty()
             && self.config.includes().is_empty()
-            && self.config.after_includes.is_none()
+            && self.config.after_includes.is_empty()
         {
             return;
         }
@@ -439,7 +439,7 @@ impl LanguageBackend for CLikeLanguageBackend<'_> {
             out.new_line();
         }
 
-        if let Some(ref line) = self.config.after_includes {
+        for line in self.config.after_includes.text_for(self.config.language) {
             write!(out, "{}", line);
             out.new_line();
         }

src/bindgen/language_backend/cython.rs

@@ -47,9 +47,9 @@ impl LanguageBackend for CythonLanguageBackend<'_> {
             write!(out, "''' Package version: {} '''", package_version);
             out.new_line();
         }
-        if let Some(ref f) = self.config.header {
+        for line in self.config.header.text_for(self.config.language) {
             out.new_line_if_not_start();
-            write!(out, "{}", f);
+            write!(out, "{}", line);
             out.new_line();
         }
 
@@ -72,7 +72,7 @@ impl LanguageBackend for CythonLanguageBackend<'_> {
             && self.config.sys_includes().is_empty()
             && self.config.includes().is_empty()
             && (self.config.cython.cimports.is_empty())
-            && self.config.after_includes.is_none()
+            && self.config.after_includes.is_empty()
         {
             return;
         }
@@ -98,7 +98,7 @@ impl LanguageBackend for CythonLanguageBackend<'_> {
             out.new_line();
         }
 
-        if let Some(ref line) = &self.config.after_includes {
+        for line in self.config.after_includes.text_for(self.config.language) {
             write!(out, "{}", line);
             out.new_line();
         }

src/bindgen/language_backend/mod.rs

@@ -199,10 +199,10 @@ pub trait LanguageBackend: Sized {
     }
 
     fn write_trailer<W: Write>(&mut self, out: &mut SourceWriter<W>, b: &Bindings) {
-        if let Some(ref f) = b.config.trailer {
+        for line in b.config.trailer.text_for(b.config.language) {
             out.new_line_if_not_start();
-            write!(out, "{}", f);
-            if !f.ends_with('\n') {
+            write!(out, "{}", line);
+            if !line.ends_with('\n') {
                 out.new_line();
             }
         }

tests/expectations/box.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box.compat.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box.cpp

@@ -1,15 +1,5 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
 template <typename T>
 using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
 
 
 #include <cstdarg>

tests/expectations/box.pyx

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
 from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
 cdef extern from *:

tests/expectations/box_both.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box_both.compat.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box_tag.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box_tag.compat.c

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdint.h>

tests/expectations/box_tag.pyx

@@ -1,17 +1,3 @@
-#if 0
-''' '
-#endif
-
-#ifdef __cplusplus
-template <typename T>
-using Box = T*;
-#endif
-
-#if 0
-' '''
-#endif
-
-
 from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, intptr_t
 from libc.stdint cimport uint8_t, uint16_t, uint32_t, uint64_t, uintptr_t
 cdef extern from *: