Some Refactoring and cleanups.

* Moved the AST datastructures into their own module.
* Collapsed the Expression Enum to just wrappers around structs
  instead of having actual structs in the definitions.
* Added a few more unit tests to ensure nothing got broken.
* Added documentation for the new structs.
* Added a unifying BinaryExpression Tuple type.

Cargo.toml

@@ -1,16 +1,17 @@
 [package]
-name = "ucg"
-version = "0.0.1"
-authors = ["Jeremy Wall <jeremy@marzhillstudios.com>"]
+name        = "ucg"
+version     = "0.0.1"
+authors     = ["Jeremy Wall <jeremy@marzhillstudios.com>"]
 description = "Runs a command on user specified triggers."
-repository = "https://github.com/zaphar/ucg"
-readme = "README.md"
-keywords = ["compiler", "config"]
-license = "Apache-2.0"
+repository  = "https://github.com/zaphar/ucg"
+readme      = "README.md"
+keywords    = ["compiler", "config"]
+license     = "Apache-2.0"
 
 [dependencies]
-nom = "^2.2"
+nom         = "^2.2"
 quick-error = "^1.2.0"
+clap        = "~2.26.0"
 
 [lib]
 name = "ucglib"

examples/test.ucg

@@ -0,0 +1,16 @@
+let dbhost = "localhost";
+let dbname = "testdb";
+
+let mk_db_conn = macro (host, port, db) => {
+    conn_string = "@:@/@" % (host, port, db)
+    host = host,
+    port = port,
+    db = db,
+};
+
+let db_conn = mk_db_conn(host, 3306, dbame);
+
+let server_config = {
+    dbconn = db_conn.conn_string,
+    tmpldir = "./templates"
+};

src/ast.rs

@@ -0,0 +1,139 @@
+// Copyright 2017 Jeremy Wall <jeremy@marzhillstudios.com>
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+pub type FieldList = Vec<(String, Expression)>; // str is expected to be a symbol
+pub type SelectorList = Vec<String>; // str is expected to always be a symbol.
+
+/// Value represents a Value in the UCG parsed AST.
+#[derive(Debug,PartialEq,Clone)]
+pub enum Value {
+    // Constant Values
+    Int(i64),
+    Float(f64),
+    String(String),
+    Symbol(String),
+    // Complex Values
+    Tuple(FieldList),
+    Selector(SelectorList),
+}
+
+impl Value {
+    pub fn type_name(&self) -> String {
+        match self {
+            &Value::Int(_) => "Integer".to_string(),
+            &Value::Float(_) => "Float".to_string(),
+            &Value::String(_) => "String".to_string(),
+            &Value::Symbol(_) => "Symbol".to_string(),
+            &Value::Tuple(_) => "Tuple".to_string(),
+            &Value::Selector(_) => "Selector".to_string(),
+        }
+    }
+
+    fn fields_to_string(v: &FieldList) -> String {
+        let mut buf = String::new();
+        buf.push_str("{\n");
+        for ref t in v.iter() {
+            buf.push_str("\t");
+            buf.push_str(&t.0);
+            buf.push_str("\n");
+        }
+        buf.push_str("}");
+        return buf;
+    }
+
+    pub fn to_string(&self) -> String {
+        match self {
+            &Value::Int(ref i) => format!("{}", i),
+            &Value::Float(ref f) => format!("{}", f),
+            &Value::String(ref s) => format!("{}", s),
+            &Value::Symbol(ref s) => format!("{}", s),
+            &Value::Tuple(ref fs) => format!("{}", Self::fields_to_string(fs)),
+            &Value::Selector(ref v) =>  v.join("."),
+        }
+    }
+}
+
+/// CallDef represents a call to a Macro that is expected to already have been
+/// defined.
+#[derive(PartialEq,Debug,Clone)]
+pub struct CallDef {
+    pub macroref: SelectorList,
+    pub arglist: Vec<Expression>,
+}
+
+/// SelectDef selects a value from a tuple with a default if the value doesn't
+/// exist.
+#[derive(PartialEq,Debug,Clone)]
+pub struct SelectDef {
+    pub val: Box<Expression>,
+    pub default: Box<Expression>,
+    pub tuple: FieldList,
+}
+
+/// MacroDef is a pure function that always returns a Tuple.
+///
+/// MacroDef's are not closures. They can not reference
+/// any values except what is defined in their arguments.
+#[derive(PartialEq,Debug,Clone)]
+pub struct MacroDef {
+    pub argdefs: Vec<String>,
+    pub fields: FieldList,
+}
+
+/// BinaryExpression represents an expression with a left and a right side.
+#[derive(Debug,PartialEq,Clone)]
+pub struct BinaryExpression(pub Value, pub Box<Expression>);
+
+/// Expression encodes an expression. Expressions compute a value from operands.
+#[derive(Debug,PartialEq,Clone)]
+pub enum Expression {
+    // Base Expression
+    Simple(Value),
+
+    // TODO(jwall): This should probably be all one type :-p
+    // Binary Expressions
+    Add(BinaryExpression),
+    Sub(BinaryExpression),
+    Mul(BinaryExpression),
+    Div(BinaryExpression),
+
+    // Complex Expressions
+    Copy(SelectorList, FieldList),
+    Grouped(Box<Expression>),
+
+    Format(String, Vec<Expression>),
+
+    Call(CallDef),
+
+    Macro(MacroDef),
+    Select(SelectDef),
+}
+
+/// Statement encodes a parsed Statement in the UCG AST.
+#[derive(Debug,PartialEq)]
+pub enum Statement {
+    // simple expression
+    Expression(Expression),
+
+    // Named bindings
+    Let {
+        name: String,
+        value: Expression,
+    },
+
+    // Include a file.
+    Import {
+        path: String,
+        name: String,
+    },
+}

src/build.rs

@@ -11,8 +11,6 @@
 //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
-use parse::{parse,Statement,Expression,Value,FieldList,SelectorList};
-
 use std::fs::File;
 use std::io::Read;
 use std::error::Error;
@@ -25,7 +23,38 @@ use std::rc::Rc;
 
 use nom;
 
+use ast::*;
 use format;
+use parse::parse;
+
+impl MacroDef {
+    pub fn eval(&self, mut args: Vec<Rc<Val>>) -> Result<Vec<(String, Rc<Val>)>, Box<Error>> {
+        // Error conditions. If the args don't match the length and types of the argdefs then this is
+        // macro call error.
+        if args.len() > self.argdefs.len() {
+            return Err(Box::new(
+                BuildError::BadArgLen(
+                    "Macro called with too many args".to_string())));
+        }
+        // If the args don't match the types required by the expressions then that is a TypeFail.
+        // If the expressions reference Symbols not defined in the MacroDef that is also an error.
+        // TODO(jwall): We should probably enforce that the Expression Symbols must be in argdefs rules
+        // at Macro definition time not evaluation time.
+        let mut scope = HashMap::new();
+        for (i, arg) in args.drain(0..).enumerate() {
+            scope.entry(self.argdefs[i].clone()).or_insert(arg.clone());
+        }
+        let b = Builder::new_with_scope(scope);
+        let mut result: Vec<(String, Rc<Val>)> = Vec::new();
+        for &(ref key, ref expr) in self.fields.iter() {
+            // We clone the expressions here because this macro may be consumed
+            // multiple times in the future.
+            let val = try!(b.eval_expr(expr.clone()));
+            result.push((key.clone(), val.clone()));
+        }
+        Ok(result)
+    }
+}
 
 quick_error! {
     #[derive(Debug,PartialEq)]
@@ -68,46 +97,7 @@ quick_error! {
 /// BuildResult is the result of a build.
 type BuildResult = Result<(), Box<Error>>;
 
-/// MacroDef is a pure function that always returns a Tuple.
-///
-/// MacroDef's are not closures. They can not reference
-/// any values except what is defined in their arguments.
-#[derive(PartialEq,Debug,Clone)]
-pub struct MacroDef {
-    argdefs: Vec<String>,
-    fields: FieldList,
-}
-
-impl MacroDef {
-    fn eval(&self, mut args: Vec<Rc<Val>>) -> Result<Vec<(String, Rc<Val>)>, Box<Error>> {
-        // Error conditions. If the args don't match the length and types of the argdefs then this is
-        // macro call error.
-        if args.len() > self.argdefs.len() {
-            return Err(Box::new(
-                BuildError::BadArgLen(
-                    "Macro called with too many args".to_string())));
-        }
-        // If the args don't match the types required by the expressions then that is a TypeFail.
-        // If the expressions reference Symbols not defined in the MacroDef that is also an error.
-        // TODO(jwall): We should probably enforce that the Expression Symbols must be in argdefs rules
-        // at Macro definition time not evaluation time.
-        let mut scope = HashMap::new();
-        for (i, arg) in args.drain(0..).enumerate() {
-            scope.entry(self.argdefs[i].clone()).or_insert(arg.clone());
-        }
-        let b = Builder::new_with_scope(scope);
-        let mut result: Vec<(String, Rc<Val>)> = Vec::new();
-        for &(ref key, ref expr) in self.fields.iter() {
-            // We clone the expressions here because this macro may be consumed
-            // multiple times in the future.
-            let val = try!(b.eval_expr(expr.clone()));
-            result.push((key.clone(), val.clone()));
-        }
-        Ok(result)
-    }
-}
-
-/// Val is the type of a value for a field in a Tuple.
+/// Val is the Intermediate representation of a compiled UCG AST.
 #[derive(PartialEq,Debug,Clone)]
 pub enum Val {
     Int(i64),
@@ -277,6 +267,64 @@ impl Builder {
         Ok(())
     }
 
+    pub fn build_file_string(&mut self, name: &str, input: String) -> BuildResult {
+        match parse((&input[..]).as_bytes()) {
+            nom::IResult::Done(_, mut stmts) => {
+                for stmt in stmts.drain(0..) {
+                    try!(self.build_stmt(stmt));
+                }
+                Ok(())
+            },
+            nom::IResult::Error(err) => Err(Box::new(err)),
+            nom::IResult::Incomplete(_) => Err(Box::new(
+                BuildError::IncompleteParse(format!("Could not parse input from file: {}", name)))),
+        }
+    }
+
+    pub fn build_file(&mut self, name: &str) -> BuildResult {
+        let mut f = try!(File::open(name));
+        let mut s = String::new();
+        // TODO(jwall): It would be nice to be able to do this with streaming
+        try!(f.read_to_string(&mut s));
+        self.build_file_string(name, s)
+    }
+
+    fn build_stmt(&mut self, stmt: Statement) -> BuildResult {
+        match stmt {
+            Statement::Let { name: sym, value: expr } => {
+                let val = try!(self.eval_expr(expr));
+                self.last = Some(val.clone());
+                match self.out.entry(sym) {
+                    Entry::Occupied(e) => {
+                        return Err(Box::new(
+                            BuildError::DuplicateBinding(
+                                format!("Let binding for {} already exists", e.key()))));
+                    },
+                    Entry::Vacant(e) => {
+                        e.insert(val);
+                    },
+                }
+            }
+            Statement::Import { path: val, name: sym } => {
+                if !self.files.contains(&val) { // Only parse the file once on import.
+                    if self.assets.get(&sym).is_none() {
+                        let mut b = Self::new();
+                        try!(b.build_file(&val));
+                        let fields: Vec<(String, Rc<Val>)> = b.out.drain().collect();
+                        let result = Rc::new(Val::Tuple(fields));
+                        self.assets.entry(sym).or_insert(result.clone());
+                        self.files.insert(val);
+                        self.last = Some(result);
+                    }
+                }
+            }
+            Statement::Expression(expr) => {
+                self.last = Some(try!(self.eval_expr(expr)));
+            }
+        };
+        Ok(())
+    }
+
     fn lookup_sym(&self, sym: &str) -> Option<Rc<Val>> {
         if self.out.contains_key(sym) {
             return Some(self.out[sym].clone());
@@ -358,9 +406,9 @@ impl Builder {
             Expression::Simple(val) => {
                 self.value_to_val(val)
             },
-            Expression::Add(v, expr) => {
+            Expression::Add(BinaryExpression(v, expr)) => {
                 let expr_result = try!(self.eval_expr(*expr));
-                let v = try!(self.value_to_val(*v));
+                let v = try!(self.value_to_val(v));
                 match *v {
                     Val::Int(i) => {
                         eval_binary_expr!(&Val::Int(ii), expr_result,
@@ -390,9 +438,9 @@ impl Builder {
                     }
                 }
             },
-            Expression::Sub(v, expr) => {
+            Expression::Sub(BinaryExpression(v, expr)) => {
                 let expr_result = try!(self.eval_expr(*expr));
-                let v = try!(self.value_to_val(*v));
+                let v = try!(self.value_to_val(v));
                 match *v {
                     Val::Int(i) => {
                         eval_binary_expr!(&Val::Int(ii), expr_result,
@@ -409,9 +457,9 @@ impl Builder {
                     }
                 }
             },
-            Expression::Mul(v, expr) => {
+            Expression::Mul(BinaryExpression(v, expr)) => {
                 let expr_result = try!(self.eval_expr(*expr));
-                let v = try!(self.value_to_val(*v));
+                let v = try!(self.value_to_val(v));
                 match *v {
                     Val::Int(i) => {
                         eval_binary_expr!(&Val::Int(ii), expr_result,
@@ -428,9 +476,9 @@ impl Builder {
                     }
                 }
             },
-            Expression::Div(v, expr) => {
+            Expression::Div(BinaryExpression(v, expr)) => {
                 let expr_result = try!(self.eval_expr(*expr));
-                let v = try!(self.value_to_val(*v));
+                let v = try!(self.value_to_val(v));
                 match *v {
                     Val::Int(i) => {
                         eval_binary_expr!(&Val::Int(ii), expr_result,
@@ -505,7 +553,7 @@ impl Builder {
                 let formatter = format::Formatter::new(tmpl, vals);
                 Ok(Rc::new(Val::String(try!(formatter.render()))))
             },
-            Expression::Call{macroref: sel, arglist: mut args} => {
+            Expression::Call(CallDef{macroref: sel, arglist: mut args}) => {
                 let v = try!(self.lookup_selector(sel));
                 if let &Val::Macro(ref m) = v.deref() {
                     // Congratulations this is actually a macro.
@@ -521,16 +569,12 @@ impl Builder {
                         // We should pretty print the selectors here.
                         format!("{} is not a Macro", v))))
             },
-            Expression::Macro{arglist: args, tuple: fields} => {
+            Expression::Macro(def) => {
                 // TODO(jwall): Walk the AST and verify that the symbols all
                 // exist as names in the arglist.
-                let md = MacroDef{
-                    argdefs: args,
-                    fields: fields,
-                };
-                Ok(Rc::new(Val::Macro(md)))
+                Ok(Rc::new(Val::Macro(def)))
             },
-            Expression::Select{val: target, default: def_expr, tuple: mut fields} => {
+            Expression::Select(SelectDef{val: target, default: def_expr, tuple: mut fields}) => {
                 // First resolve the target expression.
                 let v = try!(self.eval_expr(*target));
                 // Second ensure that the expression resolves to a string.
@@ -554,69 +598,12 @@ impl Builder {
         }
     }
 
-    pub fn build_file_string(&mut self, name: &str, input: String) -> BuildResult {
-        match parse((&input[..]).as_bytes()) {
-            nom::IResult::Done(_, mut stmts) => {
-                for stmt in stmts.drain(0..) {
-                    try!(self.build_stmt(stmt));
-                }
-                Ok(())
-            },
-            nom::IResult::Error(err) => Err(Box::new(err)),
-            nom::IResult::Incomplete(_) => Err(Box::new(
-                BuildError::IncompleteParse(format!("Could not parse input from file: {}", name)))),
-        }
-    }
-
-    pub fn build_file(&mut self, name: &str) -> BuildResult {
-        let mut f = try!(File::open(name));
-        let mut s = String::new();
-        // TODO(jwall): It would be nice to be able to do this with streaming
-        try!(f.read_to_string(&mut s));
-        self.build_file_string(name, s)
-    }
-
-    fn build_stmt(&mut self, stmt: Statement) -> BuildResult {
-        match stmt {
-            Statement::Let { name: sym, value: expr } => {
-                let val = try!(self.eval_expr(expr));
-                self.last = Some(val.clone());
-                match self.out.entry(sym) {
-                    Entry::Occupied(e) => {
-                        return Err(Box::new(
-                            BuildError::DuplicateBinding(
-                                format!("Let binding for {} already exists", e.key()))));
-                    },
-                    Entry::Vacant(e) => {
-                        e.insert(val);
-                    },
-                }
-            }
-            Statement::Import { path: val, name: sym } => {
-                if !self.files.contains(&val) { // Only parse the file once on import.
-                    if self.assets.get(&sym).is_none() {
-                        let mut b = Self::new();
-                        try!(b.build_file(&val));
-                        let fields: Vec<(String, Rc<Val>)> = b.out.drain().collect();
-                        let result = Rc::new(Val::Tuple(fields));
-                        self.assets.entry(sym).or_insert(result.clone());
-                        self.files.insert(val);
-                        self.last = Some(result);
-                    }
-                }
-            }
-            Statement::Expression(expr) => {
-                self.last = Some(try!(self.eval_expr(expr)));
-            }
-        };
-        Ok(())
-    }
 }
 
 #[cfg(test)]
 mod test {
-    use super::{Builder,Val,MacroDef};
-    use parse::{Statement,Expression,Value};
+    use super::{Builder, Val, MacroDef, SelectDef, CallDef};
+    use ast::*;
     use std::rc::Rc;
 
     fn test_expr_to_val(mut cases: Vec<(Expression,Val)>, b: Builder) {
@@ -627,11 +614,11 @@ mod test {
 
     #[test]
     fn test_eval_div_expr() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Div(Box::new(Value::Int(2)), Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Div(BinaryExpression(Value::Int(2), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Int(1)),
-            (Expression::Div(Box::new(Value::Float(2.0)), Box::new(Expression::Simple(Value::Float(2.0)))),
+            (Expression::Div(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Float(2.0))))),
              Val::Float(1.0)),
         ], b);
     }
@@ -639,20 +626,20 @@ mod test {
     #[test]
     #[should_panic(expected = "Expected Float")]
     fn test_eval_div_expr_fail() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Div(Box::new(Value::Float(2.0)), Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Div(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Float(1.0)),
         ], b);
     }
 
     #[test]
     fn test_eval_mul_expr() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Mul(Box::new(Value::Int(2)), Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Mul(BinaryExpression(Value::Int(2), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Int(4)),
-            (Expression::Mul(Box::new(Value::Float(2.0)), Box::new(Expression::Simple(Value::Float(2.0)))),
+            (Expression::Mul(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Float(2.0))))),
              Val::Float(4.0)),
         ], b);
     }
@@ -660,23 +647,20 @@ mod test {
     #[test]
     #[should_panic(expected = "Expected Float")]
     fn test_eval_mul_expr_fail() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Mul(Box::new(Value::Float(2.0)),
-                             Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Mul(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Float(1.0)),
         ], b);
     }
 
     #[test]
     fn test_eval_subtract_expr() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Sub(Box::new(Value::Int(2)),
-                             Box::new(Expression::Simple(Value::Int(1)))),
+            (Expression::Sub(BinaryExpression(Value::Int(2), Box::new(Expression::Simple(Value::Int(1))))),
              Val::Int(1)),
-            (Expression::Sub(Box::new(Value::Float(2.0)),
-                             Box::new(Expression::Simple(Value::Float(1.0)))),
+            (Expression::Sub(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Float(1.0))))),
              Val::Float(1.0)),
         ], b);
     }
@@ -684,26 +668,22 @@ mod test {
     #[test]
     #[should_panic(expected = "Expected Float")]
     fn test_eval_subtract_expr_fail() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Sub(Box::new(Value::Float(2.0)),
-                             Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Sub(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Float(1.0)),
         ], b);
     }
 
     #[test]
     fn test_eval_add_expr() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Add(Box::new(Value::Int(1)),
-                             Box::new(Expression::Simple(Value::Int(1)))),
+            (Expression::Add(BinaryExpression(Value::Int(1), Box::new(Expression::Simple(Value::Int(1))))),
              Val::Int(2)),
-            (Expression::Add(Box::new(Value::Float(1.0)),
-                             Box::new(Expression::Simple(Value::Float(1.0)))),
+            (Expression::Add(BinaryExpression(Value::Float(1.0), Box::new(Expression::Simple(Value::Float(1.0))))),
              Val::Float(2.0)),
-            (Expression::Add(Box::new(Value::String("foo".to_string())),
-                             Box::new(Expression::Simple(Value::String("bar".to_string())))),
+            (Expression::Add(BinaryExpression(Value::String("foo".to_string()), Box::new(Expression::Simple(Value::String("bar".to_string()))))),
              Val::String("foobar".to_string())),
         ], b);
     }
@@ -711,10 +691,9 @@ mod test {
     #[test]
     #[should_panic(expected = "Expected Float")]
     fn test_eval_add_expr_fail() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
-            (Expression::Add(Box::new(Value::Float(2.0)),
-                             Box::new(Expression::Simple(Value::Int(2)))),
+            (Expression::Add(BinaryExpression(Value::Float(2.0), Box::new(Expression::Simple(Value::Int(2))))),
              Val::Float(1.0)),
         ], b);
     }
@@ -795,7 +774,7 @@ mod test {
     #[test]
     #[should_panic(expected = "Unable to find Symbol tpl1")]
     fn test_expr_copy_no_such_tuple() {
-        let mut b = Builder::new();
+        let b = Builder::new();
         test_expr_to_val(vec![
             (Expression::Copy(vec!["tpl1".to_string()], Vec::new()),
              Val::Tuple(Vec::new())),
@@ -889,10 +868,10 @@ mod test {
             ],
         })));
         test_expr_to_val(vec![
-            (Expression::Call{
+            (Expression::Call(CallDef{
                 macroref: vec!["tstmac".to_string()],
                 arglist: vec![Expression::Simple(Value::String("bar".to_string()))],
-            },
+            }),
              Val::Tuple(vec![
                  ("foo".to_string(), Rc::new(Val::String("bar".to_string()))),
              ])),
@@ -911,10 +890,10 @@ mod test {
             ],
         })));
         test_expr_to_val(vec![
-            (Expression::Call{
+            (Expression::Call(CallDef{
                 macroref: vec!["tstmac".to_string()],
                 arglist: vec![Expression::Simple(Value::String("bar".to_string()))],
-            },
+            }),
              Val::Tuple(vec![
                  ("foo".to_string(), Rc::new(Val::String("bar".to_string()))),
              ])),
@@ -927,23 +906,23 @@ mod test {
         b.out.entry("foo".to_string()).or_insert(Rc::new(Val::String("bar".to_string())));
         b.out.entry("baz".to_string()).or_insert(Rc::new(Val::String("boo".to_string())));
         test_expr_to_val(vec![
-            (Expression::Select{
+            (Expression::Select(SelectDef{
                 val: Box::new(Expression::Simple(Value::Symbol("foo".to_string()))),
                 default: Box::new(Expression::Simple(Value::Int(1))),
                 tuple: vec![
                     ("bar".to_string(), Expression::Simple(Value::Int(2))),
                     ("quux".to_string(), Expression::Simple(Value::String("2".to_string()))),
                 ],
-             },
+            }),
              Val::Int(2)),
-            (Expression::Select{
+            (Expression::Select(SelectDef{
                 val: Box::new(Expression::Simple(Value::Symbol("baz".to_string()))),
                 default: Box::new(Expression::Simple(Value::Int(1))),
                 tuple: vec![
                     ("bar".to_string(), Expression::Simple(Value::Int(2))),
                     ("quux".to_string(), Expression::Simple(Value::String("2".to_string()))),
                 ],
-            },
+            }),
              // If the field doesn't exist then we get the default.
              Val::Int(1)),
         ], b);
@@ -955,14 +934,14 @@ mod test {
         let mut b = Builder::new();
         b.out.entry("foo".to_string()).or_insert(Rc::new(Val::Int(4)));
         test_expr_to_val(vec![
-            (Expression::Select{
+            (Expression::Select(SelectDef{
                 val: Box::new(Expression::Simple(Value::Symbol("foo".to_string()))),
                 default: Box::new(Expression::Simple(Value::Int(1))),
                 tuple: vec![
                     ("bar".to_string(), Expression::Simple(Value::Int(2))),
                     ("quux".to_string(), Expression::Simple(Value::String("2".to_string()))),
                 ],
-             },
+             }),
              Val::Int(2)),
         ], b);
     }
@@ -973,7 +952,7 @@ mod test {
         b.build_stmt(Statement::Let{
             name:"foo".to_string(),
             value: Expression::Simple(Value::String("bar".to_string())),
-        });
+        }).unwrap();
         test_expr_to_val(vec![
             (Expression::Simple(Value::Symbol("foo".to_string())),
              Val::String("bar".to_string())),
@@ -983,7 +962,7 @@ mod test {
     #[test]
     fn test_build_file_string() {
         let mut b = Builder::new();
-        b.build_file_string("foo.ucg", "let foo = 1;".to_string());
+        b.build_file_string("foo.ucg", "let foo = 1;".to_string()).unwrap();
         assert!(b.out.contains_key("foo"));
     }
 

src/lib.rs

@@ -17,14 +17,14 @@ extern crate nom;
 #[macro_use]
 extern crate quick_error;
 
+pub mod ast;
 pub mod parse;
 pub mod build;
-
 mod format;
 
-pub use parse::Value;
-pub use parse::Expression;
-pub use parse::Statement;
+pub use ast::Value;
+pub use ast::Expression;
+pub use ast::Statement;
 
 pub use parse::parse;
 pub use build::Builder;

src/main.rs

@@ -11,8 +11,43 @@
 //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
+#[macro_use]
+extern crate clap;
+
 extern crate ucglib;
 
-fn main() {
-    println!("hello world");
+use ucglib::build;
+
+fn do_flags<'a>() -> clap::ArgMatches<'a> {
+    clap_app!(
+        ucg =>
+            (version: crate_version!())
+            (author: crate_authors!())
+            (about: "Universal Configuration Grammar compiler.")
+            (@subcommand build =>
+             (about: "Compile a specific ucg file.")
+             (@arg INPUT: +required "Input ucg file to build.")
+            )
+            (@subcommand validate =>
+             (about: "Check a specific ucg file for errors.")
+             (@arg INPUT: +required "Input ucg file to validate.")
+            )
+    )
+        .get_matches()
+}
+
+fn main() {
+    // TODO(jwall): Read and build an actual file.
+    let app = do_flags();
+    if let Some(matches) = app.subcommand_matches("build") {
+        let file = matches.value_of("INPUT").unwrap();
+        let mut builder = build::Builder::new();
+        builder.build_file(file).unwrap();
+        println!("Build successful");
+    } else if let Some(matches) = app.subcommand_matches("validate") {
+        let file = matches.value_of("INPUT").unwrap();
+        let mut builder = build::Builder::new();
+        builder.build_file(file).unwrap();
+        println!("File Validates");
+    }
 }

src/parse.rs

@@ -30,114 +30,10 @@ use std::error::Error;
 
 use nom::{alpha, is_alphanumeric, digit};
 
+use ast::*;
+
 type ParseResult<O> = Result<O, Box<Error>>;
 
-pub type FieldList = Vec<(String, Expression)>; // str is expected to be a symbol
-pub type SelectorList = Vec<String>; // str is expected to always be a symbol.
-
-/// Value represents a Value in the UCG parsed AST.
-#[derive(Debug,PartialEq,Clone)]
-pub enum Value {
-    // Constant Values
-    Int(i64),
-    Float(f64),
-    String(String),
-    Symbol(String),
-    // Complex Values
-    Tuple(FieldList),
-    Selector(SelectorList),
-}
-
-impl Value {
-    pub fn type_name(&self) -> String {
-        match self {
-            &Value::Int(_) => "Integer".to_string(),
-            &Value::Float(_) => "Float".to_string(),
-            &Value::String(_) => "String".to_string(),
-            &Value::Symbol(_) => "Symbol".to_string(),
-            &Value::Tuple(_) => "Tuple".to_string(),
-            &Value::Selector(_) => "Selector".to_string(),
-        }
-    }
-
-    fn fields_to_string(v: &FieldList) -> String {
-        let mut buf = String::new();
-        buf.push_str("{\n");
-        for ref t in v.iter() {
-            buf.push_str("\t");
-            buf.push_str(&t.0);
-            buf.push_str("\n");
-        }
-        buf.push_str("}");
-        return buf;
-    }
-
-    pub fn to_string(&self) -> String {
-        match self {
-            &Value::Int(ref i) => format!("{}", i),
-            &Value::Float(ref f) => format!("{}", f),
-            &Value::String(ref s) => format!("{}", s),
-            &Value::Symbol(ref s) => format!("{}", s),
-            &Value::Tuple(ref fs) => format!("{}", Self::fields_to_string(fs)),
-            &Value::Selector(ref v) =>  v.join("."),
-        }
-    }
-}
-
-/// Expression encodes an expression. Expressions compute a value from operands.
-#[derive(Debug,PartialEq,Clone)]
-pub enum Expression {
-    // Base Expression
-    Simple(Value),
-
-    // Binary Expressions
-    Add(Box<Value>, Box<Expression>),
-    Sub(Box<Value>, Box<Expression>),
-    Mul(Box<Value>, Box<Expression>),
-    Div(Box<Value>, Box<Expression>),
-
-    // Complex Expressions
-    Copy(SelectorList, FieldList),
-    Grouped(Box<Expression>),
-
-    Format(String, Vec<Expression>),
-
-    Call {
-        macroref: SelectorList,
-        arglist: Vec<Expression>,
-    },
-
-    Macro {
-        arglist: Vec<String>,
-        tuple: FieldList,
-    },
-
-    Select {
-        val: Box<Expression>,
-        default: Box<Expression>,
-        tuple: FieldList,
-    },
-}
-
-/// Statement encodes a parsed Statement in the UCG AST.
-#[derive(Debug,PartialEq)]
-pub enum Statement {
-    // simple expression
-    Expression(Expression),
-
-    // Named bindings
-    Let {
-        name: String,
-        value: Expression,
-    },
-
-    // Include a file.
-    Import {
-        path: String,
-        name: String,
-    },
-}
-
 // sentinels and punctuation
 named!(doublequote, tag!("\""));
 named!(comma, tag!(","));
@@ -305,7 +201,7 @@ named!(simple_expression<Expression>,
 );
 
 fn tuple_to_add_expression(tpl: (Value, Expression)) -> ParseResult<Expression> {
-    Ok(Expression::Add(Box::new(tpl.0), Box::new(tpl.1)))
+    Ok(Expression::Add(BinaryExpression(tpl.0, Box::new(tpl.1))))
 }
 
 named!(add_expression<Expression>,
@@ -321,7 +217,7 @@ named!(add_expression<Expression>,
 );
 
 fn tuple_to_sub_expression(tpl: (Value, Expression)) -> ParseResult<Expression> {
-    Ok(Expression::Sub(Box::new(tpl.0), Box::new(tpl.1)))
+    Ok(Expression::Sub(BinaryExpression(tpl.0, Box::new(tpl.1))))
 }
 
 named!(sub_expression<Expression>,
@@ -337,7 +233,7 @@ named!(sub_expression<Expression>,
 );
 
 fn tuple_to_mul_expression(tpl: (Value, Expression)) -> ParseResult<Expression> {
-    Ok(Expression::Mul(Box::new(tpl.0), Box::new(tpl.1)))
+    Ok(Expression::Mul(BinaryExpression(tpl.0, Box::new(tpl.1))))
 }
 
 named!(mul_expression<Expression>,
@@ -353,7 +249,7 @@ named!(mul_expression<Expression>,
 );
 
 fn tuple_to_div_expression(tpl: (Value, Expression)) -> ParseResult<Expression> {
-    Ok(Expression::Div(Box::new(tpl.0), Box::new(tpl.1)))
+    Ok(Expression::Div(BinaryExpression(tpl.0, Box::new(tpl.1))))
 }
 
 named!(div_expression<Expression>,
@@ -401,10 +297,10 @@ named!(copy_expression<Expression>,
 fn tuple_to_macro(mut t: (Vec<Value>, Value)) -> ParseResult<Expression> {
     match t.1 {
         Value::Tuple(v) => {
-            Ok(Expression::Macro {
-                arglist: t.0.drain(0..).map(|s| s.to_string()).collect(),
-                tuple: v,
-            })
+            Ok(Expression::Macro(MacroDef {
+                argdefs: t.0.drain(0..).map(|s| s.to_string()).collect(),
+                fields: v,
+            }))
         }
         // TODO(jwall): Show a better version of the unexpected parsed value.
         val => {
@@ -434,11 +330,11 @@ fn tuple_to_select(t: (Expression, Expression, Value))
                        -> ParseResult<Expression> {
     match t.2 {
         Value::Tuple(v) => {
-            Ok(Expression::Select {
+            Ok(Expression::Select(SelectDef{
                 val: Box::new(t.0),
                 default: Box::new(t.1),
                 tuple: v,
-            })
+            }))
         }
         // TODO(jwall): Show a better version of the unexpected parsed value.
         val => {
@@ -480,10 +376,10 @@ named!(format_expression<Expression>,
 
 fn tuple_to_call(t: (Value, Vec<Expression>)) -> ParseResult<Expression> {
     if let Value::Selector(sl) = t.0 {
-        Ok(Expression::Call {
+        Ok(Expression::Call(CallDef{
             macroref: sl,
             arglist: t.1,
-        })
+        }))
     } else {
         Err(Box::new(ParseError::UnexpectedToken("Selector".to_string(), format!("{:?}", t.0))))
     }
@@ -605,12 +501,13 @@ named!(pub parse<Vec<Statement> >, many1!(ws!(statement)));
 #[cfg(test)]
 mod test {
     use std::str::from_utf8;
-    use super::{Statement, Expression, Value};
+    use super::{Statement, Expression, Value, MacroDef, SelectDef, CallDef};
     use super::{number, symbol, parse, field_value, tuple, grouped_expression};
     use super::{arglist, copy_expression, macro_expression, select_expression};
     use super::{format_expression, call_expression, expression};
     use super::{expression_statement, let_statement, import_statement, statement};
     use nom::IResult;
+    use ast::*;
 
     #[test]
     fn test_statement_parse() {
@@ -725,70 +622,70 @@ mod test {
                IResult::Done(&b""[..], Expression::Simple(Value::Symbol("foo".to_string()))));
         assert_eq!(expression(&b"1 + 1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Add(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Add(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1 - 1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Sub(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Sub(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1 * 1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Mul(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Mul(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1 / 1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Div(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Div(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
 
         assert_eq!(expression(&b"1+1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Add(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Add(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1-1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Sub(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Sub(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1*1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Mul(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Mul(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"1/1"[..]),
                IResult::Done(&b""[..],
-                             Expression::Div(Box::new(Value::Int(1)),
-                                             Box::new(Expression::Simple(Value::Int(1))))));
+                             Expression::Div(BinaryExpression(Value::Int(1),
+                                             Box::new(Expression::Simple(Value::Int(1)))))));
         assert_eq!(expression(&b"macro (arg1, arg2) => { foo = arg1 }"[..]),
                IResult::Done(&b""[..],
-                             Expression::Macro{
-                                 arglist: vec![
+                             Expression::Macro(MacroDef{
+                                 argdefs: vec![
                                      "arg1".to_string(),
                                      "arg2".to_string(),
                                  ],
-                                 tuple: vec![
+                                 fields: vec![
                                      ("foo".to_string(), Expression::Simple(Value::Symbol("arg1".to_string()))),
                                  ],
-                             }
+                             })
                )
     );
         assert_eq!(expression(&b"select foo, 1, { foo = 2 };"[..]),
                IResult::Done(&b""[..],
-                             Expression::Select{
+                             Expression::Select(SelectDef{
                                  val: Box::new(Expression::Simple(Value::Symbol("foo".to_string()))),
                                  default: Box::new(Expression::Simple(Value::Int(1))),
                                  tuple: vec![
                                      ("foo".to_string(), Expression::Simple(Value::Int(2)))
                                  ]
-                             }
+                             })
                )
     );
         assert_eq!(expression(&b"foo.bar (1, \"foo\")"[..]),
                IResult::Done(&b""[..],
-                             Expression::Call{
+                             Expression::Call(CallDef{
                                  macroref: vec!["foo".to_string(),"bar".to_string()],
                                  arglist: vec![
                                      Expression::Simple(Value::Int(1)),
                                      Expression::Simple(Value::String("foo".to_string())),
                                  ],
-                             }
+                             })
                )
     );
         assert_eq!(expression(&b"(1 + 1)"[..]),
@@ -796,8 +693,8 @@ mod test {
                           Expression::Grouped(
                               Box::new(
                                   Expression::Add(
-                                      Box::new(Value::Int(1)),
-                                      Box::new(Expression::Simple(Value::Int(1)))
+                                      BinaryExpression(Value::Int(1),
+                                      Box::new(Expression::Simple(Value::Int(1))))
                                   )
                               )
                           )
@@ -819,6 +716,13 @@ mod test {
                                                      Expression::Simple(Value::Int(2))])
                )
         );
+        assert_eq!(format_expression(&b"\"foo @ @\"%(1, 2)"[..]),
+               IResult::Done(&b""[..],
+                             Expression::Format("foo @ @".to_string(),
+                                                vec![Expression::Simple(Value::Int(1)),
+                                                     Expression::Simple(Value::Int(2))])
+               )
+        );
     }
 
     #[test]
@@ -831,25 +735,25 @@ mod test {
 
         assert_eq!(call_expression(&b"foo (1, \"foo\")"[..]),
                IResult::Done(&b""[..],
-                             Expression::Call{
+                             Expression::Call(CallDef{
                                  macroref: vec!["foo".to_string()],
                                  arglist: vec![
                                      Expression::Simple(Value::Int(1)),
                                      Expression::Simple(Value::String("foo".to_string())),
                                  ],
-                             }
+                             })
                )
         );
 
         assert_eq!(call_expression(&b"foo.bar (1, \"foo\")"[..]),
                IResult::Done(&b""[..],
-                             Expression::Call{
+                             Expression::Call(CallDef{
                                  macroref: vec!["foo".to_string(),"bar".to_string()],
                                  arglist: vec![
                                      Expression::Simple(Value::Int(1)),
                                      Expression::Simple(Value::String("foo".to_string())),
                                  ],
-                             }
+                             })
                )
     );
     }
@@ -863,13 +767,13 @@ mod test {
 
         assert_eq!(select_expression(&b"select foo, 1, { foo = 2 };"[..]),
                IResult::Done(&b""[..],
-                             Expression::Select{
+                             Expression::Select(SelectDef{
                                  val: Box::new(Expression::Simple(Value::Symbol("foo".to_string()))),
                                  default: Box::new(Expression::Simple(Value::Int(1))),
                                  tuple: vec![
                                      ("foo".to_string(), Expression::Simple(Value::Int(2)))
                                  ]
-                             }
+                             })
                )
     );
     }
@@ -890,13 +794,13 @@ mod test {
 
         assert_eq!(macro_expression(&b"macro (arg1, arg2) => {foo=1,bar=2}"[..]),
                IResult::Done(&b""[..],
-                             Expression::Macro{
-                                 arglist: vec!["arg1".to_string(),
+                             Expression::Macro(MacroDef{
+                                 argdefs: vec!["arg1".to_string(),
                                                "arg2".to_string()],
-                                 tuple: vec![("foo".to_string(), Expression::Simple(Value::Int(1))),
+                                 fields: vec![("foo".to_string(), Expression::Simple(Value::Int(1))),
                                              ("bar".to_string(), Expression::Simple(Value::Int(2)))
                                  ]
-                             }
+                             })
                )
     );
     }
@@ -947,9 +851,9 @@ mod test {
                           Expression::Grouped(
                               Box::new(
                                   Expression::Add(
-                                      Box::new(Value::Int(1)),
-                                      Box::new(Expression::Simple(
-                                          Value::Int(1)))
+                                      BinaryExpression(Value::Int(1),
+                                                       Box::new(Expression::Simple(
+                                                           Value::Int(1))))
                                   )
                               )
                           )
@@ -1058,8 +962,8 @@ mod test {
                        value: Expression::Simple(Value::Int(1))
                    },
                    Statement::Expression(
-                       Expression::Add(Box::new(Value::Int(1)),
-                                       Box::new(Expression::Simple(Value::Int(1))))
+                       Expression::Add(BinaryExpression(Value::Int(1),
+                                       Box::new(Expression::Simple(Value::Int(1)))))
                    )
                ]);
     }