sherpack-convert 0.4.0

// Go Template Grammar for Sherpack Converter
// Based on Go's text/template syntax
// Reference: https://pkg.go.dev/text/template

// ====================
// Top-level structure
// ====================

template = { SOI ~ element* ~ EOI }

element = _{
    action
    | raw_text
}

// Raw text is anything not inside {{ }}
raw_text = @{ (!(action_start) ~ ANY)+ }

// ====================
// Actions (template directives)
// ====================

action = {
    action_start ~ ws* ~ action_body ~ ws* ~ action_end
}

action_start = @{ "{{" ~ "-"? }
action_end = @{ "-"? ~ "}}" }

action_body = _{
    comment
    | if_action
    | else_if_action
    | else_action
    | end_action
    | range_action
    | with_action
    | define_action
    | template_action
    | block_action
    | pipeline
}

// ====================
// Comments
// ====================

comment = @{ "/*" ~ (!"*/" ~ ANY)* ~ "*/" }

// ====================
// Control flow
// ====================

if_action = { ^"if" ~ ws+ ~ pipeline }

else_if_action = { ^"else" ~ ws+ ~ ^"if" ~ ws+ ~ pipeline }

else_action = { ^"else" }

end_action = { ^"end" }

range_action = {
    ^"range" ~ ws+ ~ (range_clause ~ ws*)? ~ pipeline
}

range_clause = {
    range_vars ~ ws* ~ ":=" ~ ws*
}

range_vars = {
    variable ~ (ws* ~ "," ~ ws* ~ variable)?
}

with_action = { ^"with" ~ ws+ ~ pipeline }

// ====================
// Template definitions
// ====================

define_action = { ^"define" ~ ws+ ~ string_literal }

template_action = {
    ^"template" ~ ws+ ~ string_literal ~ (ws+ ~ pipeline)?
}

block_action = {
    ^"block" ~ ws+ ~ string_literal ~ ws+ ~ pipeline
}

// ====================
// Pipeline (core expression system)
// ====================

pipeline = {
    pipeline_decl
    | pipeline_expr
}

// Variable declaration: $x := .Value or reassignment: $x = .Value
pipeline_decl = {
    variable ~ ws* ~ (":=" | "=") ~ ws* ~ pipeline_expr
}

// Expression with optional pipe chain
pipeline_expr = {
    command ~ (ws* ~ "|" ~ ws* ~ command)*
}

// ====================
// Commands
// ====================

command = {
    parenthesized
    | function_call
    | method_call
    | field_chain
    | variable
    | literal
    | bare_identifier
}

// Parenthesized expression
parenthesized = { "(" ~ ws* ~ pipeline ~ ws* ~ ")" }

// Function call: funcName arg1 arg2
function_call = {
    !keyword ~ identifier ~ (ws+ ~ argument)+
}

// Method call on a value: .Method arg1
method_call = {
    field_chain ~ ws+ ~ argument+
}

// Bare identifier (function with no args, like "quote" or "now")
bare_identifier = {
    !keyword ~ identifier
}

// Argument to a function
argument = {
    parenthesized
    | field_chain
    | variable
    | literal
}

// ====================
// Field access
// ====================

// Field chain: .Values.image.tag or $.Values.x or just .
field_chain = @{
    root_marker? ~ "." ~ field_path?
}

root_marker = { "$" }

field_path = @{
    identifier ~ ("." ~ identifier)*
}

// ====================
// Variables
// ====================

variable = @{ "$" ~ identifier? }

// ====================
// Keywords (to avoid matching as identifiers)
// ====================

keyword = {
    (^"if" | ^"else" | ^"end" | ^"range" | ^"with" | ^"define" | ^"template" | ^"block" | "true" | "false" | "nil") ~ !ASCII_ALPHANUMERIC
}

// ====================
// Identifiers
// ====================

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

// ====================
// Literals
// ====================

literal = {
    string_literal
    | char_literal
    | number
    | boolean
    | nil
}

// String: "hello" or `raw string`
string_literal = @{
    "\"" ~ string_content ~ "\""
    | "`" ~ raw_string_content ~ "`"
}

string_content = @{
    (
        "\\" ~ ANY  // Escape sequence
        | !"\"" ~ ANY
    )*
}

raw_string_content = @{
    (!"`" ~ ANY)*
}

// Character: 'a'
char_literal = @{
    "'" ~ (("\\" ~ ANY) | (!"'" ~ ANY)) ~ "'"
}

// Numbers
number = @{
    "-"? ~ (
        "0x" ~ ASCII_HEX_DIGIT+  // Hex
        | "0o" ~ ASCII_OCT_DIGIT+  // Octal
        | "0b" ~ ASCII_BIN_DIGIT+  // Binary
        | ASCII_DIGIT+ ~ ("." ~ ASCII_DIGIT+)? ~ (^"e" ~ "-"? ~ ASCII_DIGIT+)?  // Decimal/float
    )
}

boolean = { "true" | "false" }

nil = { "nil" }

// ====================
// Whitespace (explicit handling)
// ====================

ws = _{ " " | "\t" | "\n" | "\r" }