mist/parser/src/grammar.pest

// ======================================================
// LEXICAL
// ======================================================

WHITESPACE = _{ " " | "\t" | "\r" | "\n" }
COMMENT    = _{ "//" ~ (!"\n" ~ ANY)* }

// ------------------------------------------------------
// PRIMITIVES
// ------------------------------------------------------

identifier = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHANUMERIC | "_")* }

integer = @{ ASCII_DIGIT+ }

float = @{
    ASCII_DIGIT+ ~ "." ~ ASCII_DIGIT+
}

boolean = {
    "true"
  | "false"
}

string_lit = {
    "\"" ~ inner_str ~ "\""
}

inner_str = @{
    (!"\"" ~ ("\\\"" | ANY))*
}

semicolon = _{ ";" }

static_path = {
    identifier ~ ("::" ~ identifier)*
}

// ======================================================
// PROGRAM
// ======================================================

program = {
    SOI ~ top_level* ~ EOI
}

// ======================================================
// MODIFIERS
// ======================================================

export  = { "public" }
mutable = { "mut" }
var     = { "var" }

// ======================================================
// GENERICS
// ======================================================
generic  = { identifier ~ (":" ~ static_path ~ ("+" ~ static_path)*)? }
generics = { "<" ~ (generic ~ ("," ~ generic)*)? ~ ">" }

// ======================================================
// TYPES
// ======================================================

tuple_type = {
    "(" ~ (type_expr ~ ("," ~ type_expr)*)? ~ ")"
}

path_type = {
    static_path ~ ("<" ~ (type_expr ~ ("," ~ type_expr)*)? ~ ">")?
}

ref_type = {
    mutable? ~ "*"
}

type_expr = {
    (path_type | tuple_type) ~ ref_type*
}

// ======================================================
// LITERALS
// ======================================================

literal = {
    float
  | integer
  | boolean
  | string_lit
}

// ======================================================
// PATTERNS
// ======================================================

tuple_pattern = {
    "(" ~ (identifier ~ ("," ~ identifier)*)? ~ ")"
}

named_tuple_pattern = {
    static_path ~ "(" ~ (identifier ~ ("," ~ identifier)*)? ~ ")"
}

struct_pattern = {
    static_path ~ "{" ~ (identifier ~ ("," ~ identifier)*)? ~ "}"
}

pattern = _{
    named_tuple_pattern
  | tuple_pattern
  | struct_pattern
  | literal
  | static_path
}

// ======================================================
// ATTRIBUTES / META
// ======================================================

attribute = {
    "#" ~ "[" ~ meta ~ "]"
}

mod_attribute = {
    "#" ~ "!" ~ "[" ~ meta ~ "]"
}

meta = {
    static_path ~ ("=" ~ literal | "(" ~ meta_list? ~ ")")?
}

meta_list = {
    meta ~ ("," ~ meta)* ~ ","?
}

attributes = {
    attribute*
}

// ======================================================
// DECLARATION HELPERS
// ======================================================

var_decl = {
    (var | type_expr) ~ mutable? ~ pattern
}

field = {
    export? ~ type_expr ~ identifier
}

field_list = {
    field ~ ("," ~ field)* ~ ","?
}

param_list = {
    var_decl ~ ("," ~ var_decl)* ~ ","?
}

// ======================================================
// IMPORTS / MODULES
// ======================================================

import = {
    "use" ~ "<" ~ static_path ~ ">" ~ semicolon
}

mod_package = {
    "mod" ~ identifier ~ semicolon
}

// ======================================================
// STRUCTS
// ======================================================

struct_decl = {
    export? ~ "struct" ~ identifier ~ generics? ~ "{" ~ field_list? ~ "}"
}

// ======================================================
// ENUMS
// ======================================================

enum_named = {
    identifier
}

enum_tuple = {
    identifier ~ tuple_type
}

enum_struct = {
    identifier ~ "{" ~ field_list ~ "}"
}

enum_field = _{
    enum_tuple
  | enum_struct
  | enum_named
}

enum_fields = _{
    enum_field ~ ("," ~ enum_field)* ~ ","?
}

enum_decl = {
    export? ~ "enum" ~ identifier ~ "{" ~ enum_fields ~ "}"
}

// ======================================================
// CLASSES
// ======================================================

class_constructor = {
    export? ~ "constructor" ~ "(" ~ param_list? ~ ")" ~ block
}

class_fields = {
    var_decl_statement*
}

self_param = {
    "self" ~ mutable? ~ deref_px?
}

method = {
    export? ~ type_expr ~ identifier ~ "(" ~ self_param? ~ param_list? ~ ")" ~ block
}

class_decl = {
    export? ~ "class" ~ identifier ~ "{" ~ class_fields ~ class_constructor ~ method* ~ "}"
}

// ======================================================
// FUNCTIONS
// ======================================================

function_decl = {
    export? ~ type_expr ~ identifier ~ "(" ~ param_list? ~ ")" ~ block
}

// ======================================================
// TOP LEVEL
// ======================================================

top_level = {
    (attributes ~ (import | function_decl | struct_decl | enum_decl | class_decl | mod_package))
  | mod_attribute
}

// ======================================================
// STATEMENTS
// ======================================================

block = {
    "{" ~ statement_list ~ "}"
}

statement_list = {
    statement*
}

statement = _{
    expr_stmt
  | match_stmt
  | var_decl_statement
  | assign_statement
  | if_stmt
  | while_stmt
  | c_for_stmt
  | for_stmt
  | return_stmt
  | break_stmt
  | continue_stmt
  | block
}

// ------------------------------------------------------
// BASIC STATEMENTS
// ------------------------------------------------------

expr_stmt = {
    expr ~ semicolon
}

return_stmt = {
    "return" ~ expr? ~ semicolon
}

break_stmt = {
    "break" ~ semicolon
}

continue_stmt = {
    "continue" ~ semicolon
}

var_decl_statement = {
    var_decl ~ ("=" ~ expr)? ~ semicolon
}

assign_statement = {
    expr ~ "=" ~ expr ~ semicolon
}

// ------------------------------------------------------
// CONDITIONALS
// ------------------------------------------------------

else_if = {
    "else" ~ "if" ~ "(" ~ expr ~ ")" ~ statement
}

else_if_list = {
    else_if*
}

if_stmt = {
    "if" ~ "(" ~ expr ~ ")" ~ statement ~ else_if_list ~ ("else" ~ statement)?
}

// ------------------------------------------------------
// LOOPS
// ------------------------------------------------------

while_stmt = {
    "while" ~ "(" ~ expr ~ ")" ~ statement
}

c_for_stmt = {
    "for" ~ "(" ~ statement ~ expr ~ semicolon ~ statement ~ ")" ~ statement
}

for_stmt = {
    "for" ~ "(" ~ mutable? ~ pattern ~ "in" ~ expr ~ ")" ~ statement
}

// ------------------------------------------------------
// MATCH
// ------------------------------------------------------

match_item = {
    pattern ~ "=>" ~ block
}

match_stmt = {
    "match" ~ "(" ~ expr ~ ")" ~ "{" ~ match_item* ~ "}"
}

// ======================================================
// EXPRESSIONS
// ======================================================

// ------------------------------------------------------
// TUPLES
// ------------------------------------------------------

tuple = {
    "(" ~ (expr ~ ("," ~ expr)*)? ~ ")"
}

// ------------------------------------------------------
// MACROS
// ------------------------------------------------------

macro_inner_v = {
    "(" ~ macro_inner_v* ~ ")"
  | (!("(" | ")") ~ ANY)
}

// ------------------------------------------------------
// PRIMARY EXPRESSIONS
// ------------------------------------------------------

primary = {
    literal
  | static_path
  | tuple
}

// ------------------------------------------------------
// POSTFIX EXPRESSIONS
// ------------------------------------------------------

field_px = {
    "." ~ identifier
}

call_px = {
    "(" ~ (expr ~ ("," ~ expr)*)? ~ ")"
}

macro_call_px = {
    "!" ~ "(" ~ macro_inner_v* ~ ")"
}

struct_field_decl = {
    identifier ~ ":" ~ expr
}

struct_px = {
    "{" ~ (struct_field_decl ~ ("," ~ struct_field_decl)*)? ~ ","? ~ "}"
}

index_px = {
    "[" ~ expr ~ "]"
}

binary_px = {
    bin_op ~ expr
}

postfix = {
    field_px
  | call_px
  | macro_call_px
  | struct_px
  | index_px
  | binary_px
}

// ------------------------------------------------------
// PREFIX EXPRESSIONS
// ------------------------------------------------------

deref_px = {
    "*"
}

mut_ref_px = {
    "&" ~ mutable
}

ref_px = {
    "&"
}

new_px = {
    "new"
}

not_px = {
    "!"
}

prefix = {
    deref_px
  | mut_ref_px
  | ref_px
  | new_px
  | not_px
}

prefix_list = {
    prefix*
}

// ------------------------------------------------------
// OPERATORS
// ------------------------------------------------------

bin_op = {
    "<="
  | ">="
  | "=="
  | "!="
  | "&&"
  | "||"
  | "+"
  | "-"
  | "*"
  | "/"
  | "%"
  | "<"
  | ">"
}

// ------------------------------------------------------
// EXPRESSIONS
// ------------------------------------------------------

expr = {
    prefix_list ~ primary ~ postfix*
}