pgo

Overview ¶

Package pgo defines a superset of the Go syntax and provides the ability to parse and manipulate it. pgo is used to parse versions of a gopatch change.

Key features of pgo are:

• package names are optional
• expressions and statements may be written at the top level
• ... is supported in a number of places

Syntax ¶

The following documents the syntax for pgo, assuming the syntax for Go is already provided under the "go." namespace.

// Package names and imports are optional. Only a single top-level
// declaration is allowed.
file = package? imports decl;
package = "package" go.package_name;

// import_decl is a standard Go import declarations.
imports = go.import_decl*;

// For top-level declarations, type, function/method, and constant
// declarations are assumed to be standard Go declarations. In addition to
// them, statement lists and expressions are supported at the top-level.
decl
  = go.type_decl
  | go.func_decl
  | go.const_decl
  | stmt_list
  | go.expr;

// Statement lists can open with curly braces or as-is. The two cases are
// necessary to allow disambiguating between top-level type/const
// declarations and those inlined inside a code block.
stmt_list = '{' go.stmt* '}' | go.stmt+;

Dots ¶

"...", referred to as "dots" is accepted anywhere as a statement and an expression. Note that pgo doesn't ascribe any meaning to these dots but gopatch may.