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149 lines
5.2 KiB
149 lines
5.2 KiB
// Package forge provides an api to deal with parsing configuration files.
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//
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// Config file example:
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//
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// # example.cfg
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// top_level = "a string";
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// primary {
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// primary_int = 500;
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// sub_section {
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// sub_float = 50.5; # End of line comment
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// }
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// }
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// secondary {
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// secondary_bool = true;
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// secondary_null = null;
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//
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// # Reference other config value
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// local_ref = .secondary_null;
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// global_ref = primary.sub_section.sub_float;
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//
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// # Include all files matching the provided pattern
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// include "/etc/app/*.cfg";
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// }
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//
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//
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// Config file format:
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//
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// IDENTIFIER: [_a-zA-Z]+
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// NUMBERS: [0-9]+
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//
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// BOOL: 'true' | 'false'
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// NULL: 'null'
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// INTEGER: NUMBERS | ('-' NUMBERS)
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// FLOAT: (NUMBERS '.' NUMBERS) | ('-' NUMBERS . NUMBERS)
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// STRING: '"' .* '"'
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// REFERENCE: [IDENTIFIER] ('.' IDENTIFIER)+
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// VALUE: BOOL | NULL | INTEGER | FLOAT | STRING | REFERENCE
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//
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// INCLUDE: 'include ' STRING ';'
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// DIRECTIVE: (IDENTIFIER '=' VALUE | INCLUDE) ';'
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// SECTION: IDENTIFIER '{' (DIRECTIVE | SECTION)* '}'
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// COMMENT: '#' .* NEWLINE '\n'
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//
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// CONFIG_FILE: (COMMENT | DIRECTIVE | SECTION)*
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//
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//
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// Values
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// * String:
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// Any value enclosed in double quotes (single quotes not allowed) (e.g. "string")
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// * Integer:
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// Any number without decimal places (e.g. 500)
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// * Float:
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// Any number with decimal places (e.g. 500.55)
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// * Boolean:
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// The identifiers 'true' or 'false' of any case (e.g. TRUE, True, true, FALSE, False, false)
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// * Null:
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// The identifier 'null' of any case (e.g. NULL, Null, null)
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// * Global reference:
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// An identifier which may contain periods, the references are resolved from the global
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// section (e.g. global_value, section.sub_section.value)
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// * Local reference:
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// An identifier which main contain periods which starts with a period, the references
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// are resolved from the settings current section (e.g. .value, .sub_section.value)
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//
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// Directives
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// * Comment:
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// A comment is a pound symbol ('#') followed by any text any which ends with a newline (e.g. '# I am a comment\n')
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// A comment can either be on a line of it's own or at the end of any line. Nothing can come after the comment
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// until after the newline.
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// * Directive:
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// A directive is a setting, a identifier and a value. They are in the format '<identifier> = <value>;'
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// All directives must end in a semicolon. The value can be any of the types defined above.
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// * Section:
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// A section is a grouping of directives under a common name. They are in the format '<section_name> { <directives> }'.
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// All sections must be wrapped in brackets ('{', '}') and must all have a name. They do not end in a semicolon.
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// Sections may be left empty, they do not have to contain any directives.
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// * Include:
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// An include statement tells the config parser to include the contents of another config file where the include
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// statement is defined. Includes are in the format 'include "<pattern>";'. The <pattern> can be any glob
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// like pattern which is compatible with `path.filepath.Match` http://golang.org/pkg/path/filepath/#Match
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//
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// Note about references.
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//
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// References are resolved during parsing not access (they do not act as pointers... today).
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// Meaning that if I have the following config:
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// setting = "value";
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// ref_to_setting = setting;
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//
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// During parsing when I get to `ref_to_setting` it will be resolved immediately and it's value will
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// be set to `"value"`.
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//
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// This config example, however, will raise a parsing error since it cannot resolve the reference:
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// ref_to_setting = setting;
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// setting = "value";
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//
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// Since `setting` does not exist yet.
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// This is mostly due to the naive implementation of references today. How they work may change in
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// future versions or they may disappear entirely.
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//
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package forge
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import (
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"bytes"
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"io"
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"strings"
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)
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// ParseBytes takes a []byte representation of the config file, parses it
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// and responds with `*Section` and potentially an `error` if it cannot
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// properly parse the config
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func ParseBytes(data []byte) (*Section, error) {
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return ParseReader(bytes.NewReader(data))
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}
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// ParseFile takes a string filename for the config file, parses it
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// and responds with `*Section` and potentially an `error` if it cannot
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// properly parse the configf
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func ParseFile(filename string) (*Section, error) {
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parser, err := NewFileParser(filename)
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if err != nil {
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return nil, err
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}
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err = parser.Parse()
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if err != nil {
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return nil, err
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}
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return parser.GetSettings(), nil
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}
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// ParseReader takes an `io.Reader` representation of the config file, parses it
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// and responds with `*Section` and potentially an `error` if it cannot
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// properly parse the config
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func ParseReader(reader io.Reader) (*Section, error) {
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parser := NewParser(reader)
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err := parser.Parse()
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if err != nil {
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return nil, err
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}
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return parser.GetSettings(), nil
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}
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// ParseString takes a string representation of the config file, parses it
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// and responds with `*Section` and potentially an `error` if it cannot
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// properly parse the config
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func ParseString(data string) (*Section, error) {
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return ParseReader(strings.NewReader(data))
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}
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