From ece67d35847ec89cbf4d3d13236ce5bb1d51b716 Mon Sep 17 00:00:00 2001
From: bnewbold <bnewbold@robocracy.org>
Date: Wed, 2 Nov 2016 19:06:23 -0700
Subject: skeletal scheme transpilation

---
 src/bin/mt-tool.rs      |  9 ++++++++
 src/lib.rs              |  1 +
 src/modelica_ast.rs     | 38 ++++++++++++++++++++++++++++++++++
 src/transpile_scheme.rs | 55 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+)
 create mode 100644 src/transpile_scheme.rs

diff --git a/src/bin/mt-tool.rs b/src/bin/mt-tool.rs
index 4d66339..8aac6ca 100644
--- a/src/bin/mt-tool.rs
+++ b/src/bin/mt-tool.rs
@@ -4,6 +4,7 @@ extern crate rustc_serialize;
 extern crate getopts;
 
 use modelthing::modelica_parser;
+use modelthing::transpile_scheme::TranspileScheme;
 use getopts::Options;
 use std::env;
 use std::io::Read;
@@ -81,6 +82,14 @@ fn main() {
     let cmd = matches.free[0].clone();
     match cmd.as_str() {
         "parse" => { parse_modelica_files(matches.free[1..].iter().map(|x| x.to_string()).collect()); },
+        "transpile" => {
+            if matches.free.len() != 2 {
+                println!("Expected a single path to load");
+                exit(-1);
+            }
+            let me = modelthing::load_model_entry(Path::new(&matches.free[1])).unwrap();
+            println!("{}", me.ast.repr_scheme().unwrap());
+        },
         "list" => {
             // XXX: search path?
             for m in modelthing::search_models(Path::new("examples")) {
diff --git a/src/lib.rs b/src/lib.rs
index 1f7ed27..e6b2f41 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,7 @@ extern crate toml;
 
 pub mod modelica_parser;
 pub mod modelica_ast;
+pub mod transpile_scheme;
 
 use std::path::Path;
 use std::fs;
diff --git a/src/modelica_ast.rs b/src/modelica_ast.rs
index 68eafaf..9e25b1b 100644
--- a/src/modelica_ast.rs
+++ b/src/modelica_ast.rs
@@ -1,5 +1,6 @@
 
 use std::fmt::{Debug, Formatter, Error};
+use std::collections::HashMap;
 
 #[derive(PartialEq)]
 pub struct ModelicaModel {
@@ -59,6 +60,43 @@ pub enum BinOperator {
     Subtract,
 }
 
+//// Helpers
+
+impl ModelicaModel {
+
+    pub fn get_constant_vars(&self) -> HashMap<String,Expr> {
+        let mut binds = HashMap::new();
+        for c in &self.components {
+            match c.prefix {
+                Some(ComponentPrefix::Constant) => { binds.insert(c.name.clone(), Expr::Integer(123)); },
+                Some(ComponentPrefix::Parameter) => { binds.insert(c.name.clone(), Expr::Float(4.56)); },
+                _ => (),
+            }
+        }
+        binds
+    }
+
+    pub fn get_free_vars(&self) -> Vec<String> {
+        // Start with components, and remove constants and parameters
+        let vars = self.components.iter().filter(|v| match v.prefix {
+                Some(ComponentPrefix::Constant) | Some(ComponentPrefix::Parameter) => false,
+                _ => true,
+            });
+
+        // Remove LHS (bound) vars
+        let mut outputs = vec![];
+        for eq in self.equations.iter() {
+            // TODO:
+            if let Expr::Ident(ref symb) = eq.lhs {
+                outputs.push(symb.to_string());
+            }
+        }
+        let vars = vars.filter(|v| !outputs.contains(&v.name));
+
+        vars.map(|c| c.name.clone()).collect()
+    }
+}
+
 //// Debug Implementations
 
 impl Debug for ModelicaModel {
diff --git a/src/transpile_scheme.rs b/src/transpile_scheme.rs
new file mode 100644
index 0000000..ce66d10
--- /dev/null
+++ b/src/transpile_scheme.rs
@@ -0,0 +1,55 @@
+
+use modelica_ast::*;
+
+pub trait TranspileScheme {
+    fn repr_scheme(&self) -> Result<String, String>;
+}
+
+
+impl TranspileScheme for ModelicaModel {
+    fn repr_scheme(&self) -> Result<String, String> {
+        let mut constants = vec![];
+        for (c, e) in self.get_constant_vars() {
+            constants.push(format!("({} {})",
+                c, try!(e.repr_scheme())));
+        }
+        let mut binds = vec![];
+        let mut outputs = vec![];
+        for eq in self.equations.iter() {
+            if let Expr::Ident(ref symb) = eq.lhs {
+                binds.push(format!("({} {})",
+                    symb,
+                    try!(eq.rhs.repr_scheme())));
+                outputs.push(symb.to_string());
+            } else {
+                return Err("Expected an identifier on LHS (in this partial implementation)".to_string())
+            }
+        }
+        Ok(format!(r#"(lambda ({args})
+            (let ({constants})
+              (letrec ({binds})
+                (list {outputs}))))"#,
+            args = self.get_free_vars().join(" "),
+            constants = constants.join("\n    "),
+            binds = binds.join("\n      "),
+            outputs = outputs.join(" ")))
+    }
+}
+
+impl TranspileScheme for Expr {
+    fn repr_scheme(&self) -> Result<String, String> {
+        use modelica_ast::Expr::*;
+        match *self {
+            Integer(e) => Ok(format!("{}", e)),
+            Float(e) => Ok(format!("{}", e)),
+            Ident(ref e) => Ok(format!("{}", e)),
+            Der(ref e) => Ok(format!("(der {})", try!(e.repr_scheme()))),
+            Abs(ref e) => Ok(format!("(abs {})", try!(e.repr_scheme()))),
+            BinExpr(op, ref l, ref r) =>
+                Ok(format!("({:?} {} {})",
+                    op,
+                    try!(l.repr_scheme()),
+                    try!(r.repr_scheme()))),
+        }
+    }
+}
-- 
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