Added the ability to dump the token stream or ast in bin. (#278)

* Added the ability to dump the token stream or ast in bin.

The dump functionality works both for files and REPL.

With --dump-tokens or -t for short it dumps the token stream to stdout  and --dump-ast or -a for short to dump the ast to stdout.

The dumping of tokens and ast is mutually exclusive. and when dumping it wont run the code.

* Fixed some issues with rustfmt.

* Added serde serialization and deserialization to token and the ast.

* Added a dynamic multi-format dumping of token stream and ast in bin.

- Changed the --dump-tokens and --dump-ast to be an optional argument that optionally takes a value of format type ([--opt=[val]]).
- The default format for --dump-tokens and --dump-ast is Debug format which calls std::fmt::Debug.
- Added Json and JsonMinified format for both dumps,  use serde_json internally.
- It is easy to support other format types, such as Toml with toml-rs for example.

* Made serde an optional dependency.

- Serde serialization and deserialization can be switched on by using the feature flag "serde-ast".

* Changed the JSON dumping format.

- Now Json  dumping format prints the data in minefied JSON form by default.
- Removed JsonMinified.
- Added JsonPretty as a way to dump the data in pretty printed JSON format.

* Updated the docs.

Cargo.lock

@@ -9,6 +9,7 @@ dependencies = [
  "gc_derive",
  "rand",
  "regex",
+ "serde",
  "serde_json",
  "wasm-bindgen",
 ]
@@ -610,6 +611,9 @@ name = "serde"
 version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "414115f25f818d7dfccec8ee535d76949ae78584fc4f79a6f45a904bf8ab4449"
+dependencies = [
+ "serde_derive",
+]
 
 [[package]]
 name = "serde_derive"

README.md

@@ -86,12 +86,18 @@ see [CHANGELOG](./CHANGELOG.md)
 
 ```
 USAGE:
-    boa_cli [FILE]...
+    boa_cli [OPTIONS] [FILE]...
 
 FLAGS:
     -h, --help       Prints help information
     -V, --version    Prints version information
 
+OPTIONS:
+    -a, --dump-ast <FORMAT>       Dump the ast to stdout with the given format [possible values: Debug, Json,
+                                  JsonPretty]
+    -t, --dump-tokens <FORMAT>    Dump the token stream to stdout with the given format [possible values: Debug, Json,
+                                  JsonPretty]
+
 ARGS:
     <FILE>...    The JavaScript file(s) to be evaluated
 ```

boa/Cargo.toml

@@ -11,6 +11,7 @@ exclude = ["../.vscode/*", "../Dockerfile", "../Makefile", "../.editorConfig"]
 edition = "2018"
 
 [features]
+serde-ast = ["serde"]
 default = ["wasm-bindgen"]
 
 [dependencies]
@@ -22,6 +23,7 @@ regex = "1.3.4"
 
 # Optional Dependencies
 wasm-bindgen = { version = "0.2.58", optional = true }
+serde = { version = "1.0", features = ["derive"], optional = true }
 
 [dev-dependencies]
 criterion = "0.3.1"

boa/src/lib.rs

@@ -19,6 +19,9 @@ use crate::{
     syntax::{ast::expr::Expr, lexer::Lexer, parser::Parser},
 };
 
+#[cfg(feature = "serde-ast")]
+pub use serde_json;
+
 fn parser_expr(src: &str) -> Result<Expr, String> {
     let mut lexer = Lexer::new(src);
     lexer.lex().map_err(|e| format!("SyntaxError: {}", e))?;

boa/src/syntax/ast/constant.rs

@@ -1,6 +1,10 @@
 use gc_derive::{Finalize, Trace};
 use std::fmt::{Display, Formatter, Result};
 
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A Javascript Constant
 pub enum Const {

boa/src/syntax/ast/expr.rs

@@ -8,6 +8,10 @@ use std::{
     fmt::{Display, Formatter, Result},
 };
 
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Trace, Finalize, Debug, PartialEq)]
 pub struct Expr {
     /// The expression definition
@@ -27,6 +31,7 @@ impl Display for Expr {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A Javascript Expression
 pub enum ExprDef {

boa/src/syntax/ast/keyword.rs

@@ -4,6 +4,10 @@ use std::{
     str::FromStr,
 };
 
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Copy, PartialEq, Debug)]
 /// A Javascript Keyword
 /// As specificed by <https://www.ecma-international.org/ecma-262/#sec-keywords>

boa/src/syntax/ast/op.rs

@@ -1,6 +1,9 @@
 use gc_derive::{Finalize, Trace};
 use std::fmt::{Display, Formatter, Result};
 
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
 /// Represents an operator
 pub trait Operator {
     /// Get the associativity as a boolean that is true if it goes rightwards
@@ -13,6 +16,7 @@ pub trait Operator {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A numeric operation between 2 values
 pub enum NumOp {
@@ -47,6 +51,7 @@ impl Display for NumOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A unary operation on a single value
 pub enum UnaryOp {
@@ -88,6 +93,7 @@ impl Display for UnaryOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A bitwise operation between 2 values
 pub enum BitOp {
@@ -119,6 +125,7 @@ impl Display for BitOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A comparitive operation between 2 values
 pub enum CompOp {
@@ -159,6 +166,7 @@ impl Display for CompOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A logical operation between 2 boolean values
 pub enum LogOp {
@@ -181,6 +189,7 @@ impl Display for LogOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A binary operation between 2 values
 pub enum BinOp {
@@ -240,6 +249,7 @@ impl Display for BinOp {
     }
 }
 
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, Trace, Finalize, PartialEq)]
 /// A binary operation between 2 values
 pub enum AssignOp {

boa/src/syntax/ast/pos.rs

@@ -1,3 +1,7 @@
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, Copy, PartialEq, Debug)]
 /// A position in the Javascript source code
 /// Stores both the column number and the line number

boa/src/syntax/ast/punc.rs

@@ -1,5 +1,9 @@
 use std::fmt::{Display, Error, Formatter};
 
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(PartialEq, Clone, Copy, Debug)]
 /// Punctuation
 pub enum Punctuator {

boa/src/syntax/ast/token.rs

@@ -1,9 +1,12 @@
 use crate::syntax::ast::{keyword::Keyword, pos::Position, punc::Punctuator};
 use std::fmt::{Debug, Display, Formatter, Result};
 
-#[derive(Clone, PartialEq)]
+#[cfg(feature = "serde-ast")]
+use serde::{Deserialize, Serialize};
+
 /// Represents a token
-#[derive(Debug)]
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone, PartialEq)]
 pub struct Token {
     /// The token Data
     pub data: TokenData,
@@ -38,7 +41,7 @@ impl Debug for VecToken {
         write!(f, "{}", buffer)
     }
 }
-
+#[cfg_attr(feature = "serde-ast", derive(Serialize, Deserialize))]
 #[derive(Clone, PartialEq, Debug)]
 /// Represents the type of Token
 pub enum TokenData {

boa_cli/Cargo.toml

@@ -11,5 +11,5 @@ exclude = ["../.vscode/*", "../Dockerfile", "../Makefile", "../.editorConfig"]
 edition = "2018"
 
 [dependencies]
-Boa = { path = "../boa", default-features = false }
+Boa = { path = "../boa", features = ["serde-ast"], default-features = false }
 structopt = "0.3.9"

boa_cli/src/main.rs

@@ -3,18 +3,140 @@
 #![allow(clippy::cognitive_complexity)]
 
 use boa::builtins::console::log;
+use boa::serde_json;
+use boa::syntax::ast::{expr::Expr, token::Token};
 use boa::{exec::Executor, forward_val, realm::Realm};
-use std::io;
+use std::io::{self, Write};
 use std::{fs::read_to_string, path::PathBuf};
+use structopt::clap::arg_enum;
 use structopt::StructOpt;
+
 /// CLI configuration for Boa.
+//
+// Added #[allow(clippy::option_option)] because to StructOpt an Option<Option<T>>
+// is an optional argument that optionally takes a value ([--opt=[val]]).
+// https://docs.rs/structopt/0.3.11/structopt/#type-magic
+#[allow(clippy::option_option)]
 #[derive(Debug, StructOpt)]
 #[structopt(author, about)]
 struct Opt {
     /// The JavaScript file(s) to be evaluated.
     #[structopt(name = "FILE", parse(from_os_str))]
     files: Vec<PathBuf>,
+
+    /// Dump the token stream to stdout with the given format.
+    #[structopt(
+        long,
+        short = "-t",
+        value_name = "FORMAT",
+        possible_values = &DumpFormat::variants(),
+        case_insensitive = true,
+        conflicts_with = "dump-ast"
+    )]
+    dump_tokens: Option<Option<DumpFormat>>,
+
+    /// Dump the ast to stdout with the given format.
+    #[structopt(
+        long,
+        short = "-a",
+        value_name = "FORMAT",
+        possible_values = &DumpFormat::variants(),
+        case_insensitive = true
+    )]
+    dump_ast: Option<Option<DumpFormat>>,
+}
+
+impl Opt {
+    /// Returns whether a dump flag has been used.
+    fn has_dump_flag(&self) -> bool {
+        self.dump_tokens.is_some() || self.dump_ast.is_some()
+    }
+}
+
+arg_enum! {
+    /// The different types of format available for dumping.
+    ///
+    // NOTE: This can easily support other formats just by
+    // adding a field to this enum and adding the necessary
+    // implementation. Example: Toml, Html, etc.
+    //
+    // NOTE: The fields of this enum are not doc comments because
+    // arg_enum! macro does not support it.
+    #[derive(Debug)]
+    enum DumpFormat {
+        // This is the default format that you get from std::fmt::Debug.
+        Debug,
+
+        // This is a minified json format.
+        Json,
+
+        // This is a pretty printed json format.
+        JsonPretty,
+    }
+}
+
+/// Lexes the given source code into a stream of tokens and return it.
+///
+/// Returns a error of type String with a message,
+/// if the source has a syntax error.
+fn lex_source(src: &str) -> Result<Vec<Token>, String> {
+    use boa::syntax::lexer::Lexer;
+
+    let mut lexer = Lexer::new(src);
+    lexer.lex().map_err(|e| format!("SyntaxError: {}", e))?;
+    Ok(lexer.tokens)
+}
+
+/// Parses the the token stream into a ast and returns it.
+///
+/// Returns a error of type String with a message,
+/// if the token stream has a parsing error.
+fn parse_tokens(tokens: Vec<Token>) -> Result<Expr, String> {
+    use boa::syntax::parser::Parser;
+
+    Parser::new(tokens)
+        .parse_all()
+        .map_err(|e| format!("ParsingError: {}", e))
 }
+
+/// Dumps the token stream or ast to stdout depending on the given arguments.
+///
+/// Returns a error of type String with a error message,
+/// if the source has a syntax or parsing error.
+fn dump(src: &str, args: &Opt) -> Result<(), String> {
+    let tokens = lex_source(src)?;
+
+    if let Some(ref arg) = args.dump_tokens {
+        match arg {
+            Some(format) => match format {
+                DumpFormat::Debug => println!("{:#?}", tokens),
+                DumpFormat::Json => println!("{}", serde_json::to_string(&tokens).unwrap()),
+                DumpFormat::JsonPretty => {
+                    println!("{}", serde_json::to_string_pretty(&tokens).unwrap())
+                }
+            },
+            // Default token stream dumping format.
+            None => println!("{:#?}", tokens),
+        }
+    } else if let Some(ref arg) = args.dump_ast {
+        let ast = parse_tokens(tokens)?;
+
+        match arg {
+            Some(format) => match format {
+                DumpFormat::Debug => println!("{:#?}", ast),
+                DumpFormat::Json => println!("{}", serde_json::to_string(&ast).unwrap()),
+                DumpFormat::JsonPretty => {
+                    println!("{}", serde_json::to_string_pretty(&ast).unwrap())
+                }
+            },
+            // Default ast dumping format.
+            None => println!("{:#?}", ast),
+        }
+    }
+
+    Ok(())
+}
+
 pub fn main() -> Result<(), std::io::Error> {
     let args = Opt::from_args();
 
@@ -25,9 +147,16 @@ pub fn main() -> Result<(), std::io::Error> {
     for file in &args.files {
         let buffer = read_to_string(file)?;
 
-        match forward_val(&mut engine, &buffer) {
+        if args.has_dump_flag() {
-            Ok(v) => print!("{}", v.to_string()),
+            match dump(&buffer, &args) {
-            Err(v) => eprint!("{}", v.to_string()),
+                Ok(_) => {}
+                Err(e) => eprintln!("{}", e),
+            }
+        } else {
+            match forward_val(&mut engine, &buffer) {
+                Ok(v) => print!("{}", v.to_string()),
+                Err(v) => eprint!("{}", v.to_string()),
+            }
         }
     }
 
@@ -37,10 +166,20 @@ pub fn main() -> Result<(), std::io::Error> {
 
             io::stdin().read_line(&mut buffer)?;
 
-            match forward_val(&mut engine, buffer.trim_end()) {
+            if args.has_dump_flag() {
-                Ok(v) => println!("{}", v.to_string()),
+                match dump(&buffer, &args) {
-                Err(v) => eprintln!("{}", v.to_string()),
+                    Ok(_) => {}
+                    Err(e) => eprintln!("{}", e),
+                }
+            } else {
+                match forward_val(&mut engine, buffer.trim_end()) {
+                    Ok(v) => println!("{}", v.to_string()),
+                    Err(v) => eprintln!("{}", v.to_string()),
+                }
             }
+
+            // The flush is needed because where in a REPL and we do not want buffering.
+            std::io::stdout().flush().unwrap();
         }
     }
 

docs/debugging.md

@@ -13,7 +13,16 @@ These are added in order of how the code is read:
 The first thing boa will do is generate tokens from source code.
 If the token generation is wrong the rest of the operation will be wrong, this is usually a good starting place.
 
-Navigate to `parser_expr` in [lib.rs](../src/lib/lib.rs#L48) and add `dbg!(&tokens);` just below tokens to see the array of token output. You code should look like this:
+To print the tokens to stdout, you can use the `boa_cli` command-line flag `--dump-tokens`, which can optionally take a format type. Supports these formats: `Debug`, `Json`, `JsonPretty`. By default it is the `Debug` format.
+```bash
+cargo run -- test.js --dump-tokens # token dump format is Debug by default.
+```
+or with interactive mode (REPL):
+```bash
+cargo run -- --dump-tokens # token dump format is Debug by default.
+```
+
+Or you can do it manually by navigating to `parser_expr` in [lib.rs](../boa/src/lib.rs#L25) and add `dbg!(&tokens);` just below tokens to see the array of token output. You code should look like this:
 
 ```rust
     let mut lexer = Lexer::new(src);
@@ -22,18 +31,32 @@ Navigate to `parser_expr` in [lib.rs](../src/lib/lib.rs#L48) and add `dbg!(&toke
     dbg!(&tokens);
     ...
 ```
-
 Seeing the order of tokens can be a big help to understanding what the parser is working with.
 
+**Note:** flags `--dump-tokens` and `--dump-ast` are mutually exclusive. When using the flag `--dump-tokens`, the code will not be executed.
+
 ## Expressions
 
 Assuming the tokens looks fine, the next step is to see the AST.
-You can output the expressions in [forward](../src/lib/lib.rs#L57), add `dbg!(&expr);`
+You can use the `boa_cli` command-line flag `--dump-ast`, which can optionally take a format type. Supports these formats: `Debug`, `Json`, `JsonPretty`. By default it is the `Debug` format.
-This will print out the entire parse tree.
+
+Dumping the AST of a file:
+```bash
+cargo run -- test.js --dump-ast # AST dump format is Debug by default.
+```
+or with interactive mode (REPL):
+```bash
+cargo run -- --dump-ast # AST dump format is Debug by default.
+```
+Or manually, you can output the expressions in [forward](../boa/src/lib.rs#L36), add `dbg!(&expr);`
+
+These methods will print out the entire parse tree.
+
+**Note:** flags `--dump-tokens` and `--dump-ast` are mutually exclusive. When using the flag `--dump-ast`, the code will not be executed.
 
 ## Execution
 
-Once the tree has been generated [exec](../src/lib/exec.rs#L66) will begin to run through each expression. If the tokens and tree looks fine, you can start looking here.  
+Once the tree has been generated [exec](../boa/src/lib.rs#L67) will begin to run through each expression. If the tokens and tree looks fine, you can start looking here.
 I usually just add `dbg!()` in the relevent places to see what the output is at the time.
 
 ## Debugger