feat: add support for preprocessor

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cxx2flow"
-version = "0.5.5"
+version = "0.5.6"
 edition = "2018"
 authors = ["mgt <[email protected]>"] 
 description = "Convert your C/C++ code to control flow chart"

README-en.md

@@ -0,0 +1,90 @@
+# cxx2flow
+
+[简体中文](README.md) | [English](README-en.md)
+
+Turn your C/C++ code into flowchart
+
+## Demo
+
+For more demo please refer to [GALLERY](gallery.md)
+
+Two different styles：
+| | |
+|:-:|:-:|
+| polyline | smooth |
+|![ployline](assets/polyline.svg)|![curve](assets/curve.svg)|
+
+```cpp
+inline int read() {  //快读
+  char c = getchar();
+  int x = 0, f = 1;
+  while (c < '0' || c > '9') {
+    if (c == '-') f = -1;
+    c = getchar();
+  }
+  while (c >= '0' && c <= '9') {
+    x = x * 10 + c - '0';
+    c = getchar();
+  }
+  return x * f;
+}
+```
+
+### Error reporting
+
+![error reporting](assets/error_reporting.png)
+
+## Installation
+
+### Compile from source
+
+```bash
+cargo install cxx2flow
+```
+
+### Prebuilt binary
+
+It is recommended to download prebuilt binary from [Github Release](https://github.com/Enter-tainer/cxx2flow/releases).
+
+## Usage
+
+To compile the generated dot file, you need graphviz. You can also copy the output to online graphviz services such as http://magjac.com/graphviz-visual-editor/ .
+
+```
+cxx2flow 0.5.6
+mgt <[email protected]>
+Convert your C/C++ code to control flow chart
+
+USAGE:
+    cxx2flow [OPTIONS] <INPUT> [FUNCTION]
+
+ARGS:
+    <INPUT>       Sets the input file. e.g. test.cpp
+    <FUNCTION>    The function you want to convert. e.g. main [default: main]
+
+OPTIONS:
+    -c, --curly              Sets the style of the flow chart.
+                             If specified, output flow chart will have curly connection line.
+        --cpp                Use C preprocessor.
+    -h, --help               Print help information
+    -o, --output <OUTPUT>    Sets the output file.
+                             If not specified, result will be directed to stdout.
+                             e.g. graph.dot
+    -t, --tikz               Use tikz backend.
+    -V, --version            Print version information
+
+Note that you need to manually compile the dot file using graphviz to get SVG or PNG files.
+
+EXAMPLES:
+    cxx2flow test.cpp | dot -Tpng -o test.png
+    cxx2flow main.cpp my_custom_func | dot -Tsvg -o test.svg
+
+Please give me star if this application helps you!
+如果这个应用有帮助到你，请给我点一个 star！
+https://github.com/Enter-tainer/cxx2flow
+```
+
+## Limitations
+
+- The support of preprocessor is based on `cpp`, and is disabled by default. `--cpp` flag is needed to enable it. It will fail if `cpp` does not exist in `PATH`.
+- Supported control flow keyword: while，for，if，break，continue，break，return，switch, goto, do-while。

README.md

@@ -1,5 +1,7 @@
 # cxx2flow
 
+[简体中文](README.md) | [English](README-en.md)
+
 将 C/C++ 代码转换为流程图
 
 ## 效果
@@ -51,7 +53,7 @@ cargo install cxx2flow
 为了编译生成的 dot 文件，你需要安装 graphviz，并将其添加到 PATH 中。也可以将生成的结果复制进在线的 graphviz 服务中，如 http://magjac.com/graphviz-visual-editor/ 。
 
 ```
-cxx2flow 0.5.5
+cxx2flow 0.5.6
 mgt <[email protected]>
 Convert your C/C++ code to control flow chart
 
@@ -65,6 +67,7 @@ ARGS:
 OPTIONS:
     -c, --curly              Sets the style of the flow chart.
                              If specified, output flow chart will have curly connection line.
+        --cpp                Use C preprocessor.
     -h, --help               Print help information
     -o, --output <OUTPUT>    Sets the output file.
                              If not specified, result will be directed to stdout.
@@ -85,5 +88,5 @@ https://github.com/Enter-tainer/cxx2flow
 
 ## 限制
 
-- 不支持预处理器，如 include, ifdef, ifndef...
+- 对于预处理器的支持基于 `cpp` ，默认关闭，需要使用 `--cpp` 参数手动启用。如果 `PATH` 中不存在 `cpp` 则会失败。
 - 支持的控制流语句有：while，for，if，break，continue，break，return，switch, goto, do-while。

assets/cpp.c

@@ -0,0 +1,9 @@
+#define TEST
+
+int main() {
+#ifdef TEST
+  int a = 0;
+#else
+  int a = 1;
+#endif
+}

src/main.rs

@@ -1,3 +1,9 @@
+use std::{
+    io::Write,
+    process::{self, Stdio},
+};
+
+use itertools::Itertools;
 use once_cell::sync::Lazy;
 
 use clap::Parser;
@@ -57,6 +63,9 @@ If specified, output flow chart will have curly connection line."
     )]
     curly: bool,
 
+    #[clap(long, help("Use C preprocessor."))]
+    cpp: bool,
+
     #[clap(short, long, help("Use tikz backend."))]
     tikz: bool,
 
@@ -70,11 +79,32 @@ If specified, output flow chart will have curly connection line."
     function: String,
 }
 
-
 fn main() -> miette::Result<()> {
     miette::set_panic_hook();
     let args = Args::parse();
-    let content = std::fs::read(&args.input).into_diagnostic()?;
+    let content = if args.cpp {
+        let content = std::fs::read(&args.input).into_diagnostic()?;
+        let mut cpp = process::Command::new("cpp")
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .spawn()
+            .into_diagnostic()?;
+        if let Some(mut child_stdin) = cpp.stdin.take() {
+            child_stdin.write_all(&content).into_diagnostic()?;
+        }
+        cpp.wait_with_output().into_diagnostic()?.stdout
+    } else {
+        std::fs::read(&args.input).into_diagnostic()?
+    };
+    let content = Itertools::intersperse(
+        String::from_utf8(content)
+            .unwrap()
+            .lines()
+            .filter(|x| !x.starts_with('#')),
+        "\n",
+    )
+    .collect::<String>()
+    .into_bytes();
     let res = generate(
         &content,
         &args.input,