ogdl

package module
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README

OGDL for Go

This library is being refactored. If you depend on the stable version, import gopkg.in/rveen/ogdl.v1 instead.

Package ogdl is used to process OGDL, the Ordered Graph Data Language.

OGDL is a textual format to write trees or graphs of text, where indentation and spaces define the structure. Here is an example:

network
  ip 192.168.1.100
  gw 192.168.1.9

The language is simple, either in its textual representation or its number of productions (the specification rules), allowing for compact implementations.

OGDL character streams are normally formed by Unicode characters, and encoded as UTF-8 strings, but any encoding that is ASCII transparent is compatible with the specification and the implementations.

This implementation does not support cyles (OGDL Level 2).

Documentation

The documentation of the package is kindly generated by godoc.org.

Installation

go get github.com/rveen/ogdl

go get gopkg.in/rveen/ogdl.v1  (for the previous -stable- version)

Discussion

There is a list: ogdl-go.

Example: a configuration file

If we have a text file 'conf.ogdl' like this:

eth0
  ip
    192.168.1.1
  gateway
    192.168.1.10
  mask
    255.255.255.0
  timeout
    20

then,

g := ogdl.FromFile("conf.ogdl")
ip := g.Get("eth0.ip").String()
to := g.Get("eth0.timeout").Int64(60)
println("ip:",ip,", timeout:",to)

will print

ip: 192.168.1.1, timeout: 20

If the timeout parameter were not present, then the default value (60) will be assigned to 'to'.

Documentation

Overview

Package ogdl is used to process OGDL, the Ordered Graph Data Language.

OGDL is a textual format to write trees or graphs of text, where indentation and spaces define the structure. Here is an example: 

network
  ip 192.168.1.100
  gw 192.168.1.9

The languange is simple, either in its textual representation or its number of productions (the specification rules), allowing for compact implementations.

OGDL character streams are normally formed by Unicode characters, and encoded as UTF-8 strings, but any encoding that is ASCII transparent is compatible with the specification.

See the full spec at http://ogdl.org.

Installation

To install this package just do: 

go get github.com/rveen/ogdl

An example

If we have a text file 'config.ogdl' containing: 

eth0
  ip
    192.168.1.1
  gateway
    192.168.1.10
  mask
    255.255.255.0
  timeout
    20

then, 

g := ogdl.FromFile("config.ogdl")
ip := g.Get("eth0.ip").String()
to := g.Get("eth0.timeout").Int64(60)

println("ip:",ip,", timeout:",to)

will print 

ip: 192.168.1.1, timeout: 20

If the timeout parameter was not present, then the default value (60) will be assigned to 'to'. The default value is optional, but be aware that Int64() will return 0 in case that the parameter doesn't exist.

The configuration file can be written in a conciser way: 

eth0
  ip      192.168.1.1
  gateway 192.168.1.10
  mask    255.255.255.0
  timeout 20

A template example

The package includes a template processor. It takes an arbitrary input stream with some variables in it, and produces an output stream with the variables resolved out of a Graph object which acts as context.

For example (given the previous config file): 

g := ogdl.FromFile("config.ogdl")
t := ogdl.NewTemplate("The gateway's IP is $eth0.gateway")
b := t.Process(g)

string(b) is then: 

The gateway's IP is 192.168.1.10

Function signature conventions

Some rules are followed: 

.<Type>()      Return the first subnode content converted to the specified type.

.This<Type>()  Return the node content itself converted to the specified type.

.Get()         Return the specified path as a (possible nil) *Graph object.

.Get<Type>()   Return the specified path converted to the specified type.
               These series of functions return value and error.

Index

Examples

Constants

View Source 
const (
	TypeExpression = "!e"
	TypePath       = "!p"
	TypeVariable   = "!v"
	TypeSelector   = "!s"
	TypeIndex      = "!i"
	TypeGroup      = "!g"
	TypeArguments  = "!a"
	TypeTemplate   = "!t"
	TypeString     = "!string"

	TypeIf    = "!if"
	TypeEnd   = "!end"
	TypeElse  = "!else"
	TypeFor   = "!for"
	TypeBreak = "!break"
)

Nodes containing these strings are special

Variables

View Source 
var (
	// ErrInvalidUnread reports an unsuccessful UnreadByte or UnreadRune
	ErrInvalidUnread = errors.New("invalid use of UnreadByte or UnreadRune")

	// ErrEOS indicates the end of the stream
	ErrEOS = errors.New("EOS")

	// ErrSpaceNotUniform indicates mixed use of spaces and tabs for indentation
	ErrSpaceNotUniform = errors.New("space has both tabs and spaces")

	// ErrUnterminatedQuotedString is obvious.
	ErrUnterminatedQuotedString = errors.New("quoted string not terminated")

	ErrNotANumber       = errors.New("not a number")
	ErrNotFound         = errors.New("not found")
	ErrIncompatibleType = errors.New("incompatible type")
	ErrNilReceiver      = errors.New("nil function receiver")
	ErrInvalidIndex     = errors.New("invalid index")
	ErrFunctionNoGraph  = errors.New("functions doesn't return *Graph")
	ErrInvalidArgs      = errors.New("invalid arguments or nil receiver")
)

Functions

func IsBreakChar 

func IsBreakChar(c byte) bool

IsBreakChar returns true for 10 and 13 (newline and carriage return)

func IsDigit 

func IsDigit(c rune) bool

IsDigit returns true if the given character a numeric digit, as per Unicode.

func IsEndChar 

func IsEndChar(c byte) bool

IsEndChar returns true for all integers < 32 that are not newline, carriage return or tab.

func IsEndRune 

func IsEndRune(c rune) bool

IsEndRune returns true for all integers < 32 that are not newline, carriage return or tab.

func IsLetter 

func IsLetter(c rune) bool

IsLetter returns true if the given character is a letter, as per Unicode.

func IsSpaceChar 

func IsSpaceChar(c byte) bool

IsSpaceChar returns true for space and tab

func IsTextChar 

func IsTextChar(c byte) bool

IsTextChar returns true for all integers > 32 and are not OGDL separators (parenthesis and comma)

Types

type Graph 

type Graph struct {
	This interface{}
	Out  []*Graph
}

Graph is a node with outgoing pointers to other Graph objects. It is implemented as a named list.

func FromBinary 

func FromBinary(b []byte) *Graph

FromBinary converts an OGDL binary stream of bytes into a Graph.

func FromBinaryFile 

func FromBinaryFile(file string) *Graph

FromBinaryFile converts an OGDL binary stream of bytes into a Graph.

func FromBinaryReader 

func FromBinaryReader(r io.Reader) *Graph

FromBinaryReader converts an OGDL binary stream of bytes into a Graph.

func FromBytes 

func FromBytes(b []byte) *Graph

FromBytes parses OGDL text contained in a byte array. It returns a *Graph

func FromFile 

func FromFile(s string) *Graph

FromFile parses OGDL text contained in a file. It returns a Graph

func FromJSON 

func FromJSON(buf []byte) (*Graph, error)

FromJSON converts a JSON text stream into OGDL.

Json types returned by Decode/Unmarshall: - bool, for JSON booleans - int64 / float64, for JSON numbers - string, for JSON strings - []interface{}, for JSON arrays - map[string]interface{}, for JSON objects - nil for JSON null

TODO I'm not sure about not giving lists a root node, but we need to avoid both useless nesting and also post-simplification (and its unwanted side effects). But, for example [ "a", [ "b", "c" ] ] will be returned as: 

a
b
c

func FromReader 

func FromReader(r io.Reader) *Graph

FromReader parses OGDL text coming from a generic io.Reader

func FromString 

func FromString(s string) *Graph

FromString parses OGDL text from the given string. It returns a *Graph

func FromStringTypes 

func FromStringTypes(s string) *Graph

FromStringTypes parses OGDL text from the given string. It returns a *Graph. Basic types found in the string are converted to their correspongind Go types (either string | int64 | float64 | bool).

func New 

func New(n interface{}) *Graph

New returns a pointer to Graph initialized to the object given.

func NewExpression 

func NewExpression(s string) *Graph

NewExpression parses an expression in text format (given in the string) to a Graph, in the form of a suitable syntax tree. 

expression := expr1 (op2 expr1)*
expr1 := path | constant | op1 path | op1 constant | '(' expr ')' | op1 '(' expr ')'
constant ::= quoted | number

func NewPath 

func NewPath(s string) *Graph

NewPath takes a Unicode string representing an OGDL path, parses it and returns it as a Graph object.

It also parses extended paths, as those used in templates, which may have argument lists.

func NewTemplate 

func NewTemplate(s string) *Graph

NewTemplate parses a text template given as a string and converts it to a Graph. Templates have fixed and variable parts. Variables all begin with '$'.

A template is a text file in any format: plain text, HTML, XML, OGDL or whatever. The dolar sign acts as an escape character that switches from the text to the variable plane. Parsed templates are converted back to text by evaluating the variable parts against a Graph object, by means of the Process() method.

Template grammar 

template ::= ( text | variable )*

variable ::= ('$' path) | ('$' '(' expression ')') | ('$' '{' expression '}')
path ::= as defined in path.go
expression ::= as defined in expression.go

Some variables act as directives: $if, $else, $end, $for, $break. 

$if(expression)
$else
$end

$for(destPath,sourcepath)
  $break
$end
Example 
p := NewTemplate("Hello, $user")

g := New("_")
g.Add("user").Add("Jenny")

fmt.Println(string(p.Process(g)))

Output:

Hello, Jenny

func NewTemplateFromBytes 

func NewTemplateFromBytes(b []byte) *Graph

NewTemplateFromBytes has the same function as NewTemplate except that the input stream is a byte array.

func (*Graph) Add 

func (g *Graph) Add(n interface{}) *Graph

Add adds a subnode to the current node.

func (*Graph) AddNodes 

func (g *Graph) AddNodes(g2 *Graph) *Graph

AddNodes adds subnodes of the given Graph to the current node.

func (*Graph) Binary 

func (g *Graph) Binary() []byte

Binary converts a Graph to a binary OGDL byte stream.

func (*Graph) Bool 

func (g *Graph) Bool(def ...bool) bool

Bool returns the node as a boolean. If the node is not a boolean, it returns false, or the default value if given.

func (*Graph) Bytes 

func (g *Graph) Bytes() []byte

Bytes returns the graph as []byte, or nil if not possble.

func (*Graph) Check 

func (g *Graph) Check(x *Graph) (bool, string)

Check returns true if the Graph given as a parameter conforms to the schema represented by the receiver Graph.

Example 
schema := FromString("a !int\nb !string\nc !float\nd !bool")
g := FromString("a 1\nb s\nc 1.0\nd true")

b, message := schema.Check(g)
fmt.Println(b, message)

Output:

true

func (*Graph) Clear 

func (g *Graph) Clear()

Clear removes all subnodes

func (*Graph) Clone 

func (g *Graph) Clone() *Graph

Clone returns a copy of the current graph.

Warning (from the Go faq): Copying an interface value makes a copy of the thing stored in the interface value. If the interface value holds a struct, copying the interface value makes a copy of the struct. If the interface value holds a pointer, copying the interface value makes a copy of the pointer, but not the data it points to.

func (*Graph) Copy 

func (g *Graph) Copy(c *Graph)

Copy adds a copy of the graph given to the current graph.

Warning (from the Go faq): Copying an interface value makes a copy of the thing stored in the interface value. If the interface value holds a struct, copying the interface value makes a copy of the struct. If the interface value holds a pointer, copying the interface value makes a copy of the pointer, but not the data it points to.

func (*Graph) Create 

func (g *Graph) Create(s string) *Graph

Create returns the first subnode whose string value is equal to the given string, with its subnodes deleted. If not found, the node is created and returned.

func (*Graph) Delete 

func (g *Graph) Delete(n interface{})

Delete removes all subnodes with the given content

func (*Graph) DeleteAt 

func (g *Graph) DeleteAt(i int)

DeleteAt removes a subnode by index

func (*Graph) Equals 

func (g *Graph) Equals(c *Graph) bool

Equals returns true if the given graph and the receiver graph are equal.

func (*Graph) Eval 

func (g *Graph) Eval(e *Graph) (interface{}, error)

Eval takes a parsed expression and evaluates it in the context of the current graph.

func (*Graph) Find 

func (g *Graph) Find(re string) (*Graph, error)

Find returns a Graph with all subnodes that match the regular expression given. It only walks through the subnodes of the current Graph. If the regex doesn't compile, an error will be returned. If the result set is empty, both return values are nil (no error is signaled).

func (*Graph) Float64 

func (g *Graph) Float64(def ...float64) float64

Float64 returns the node as a float64. If the node is not a number, it return NaN, or the default value if given.

func (*Graph) Get 

func (g *Graph) Get(s string) *Graph

Get recurses a Graph following a given path and returns the result.

This function returns a *Graph in any condition. When there is nothing to return, a nil Graph is returned. This behavior is designed so that the next function in a chain never gets an invalid receiver, avoiding null pointer errors.

OGDL Path: elements are separated by '.' or [] or {} index := [N] selector := {N} tokens can be quoted

func (*Graph) GetAt 

func (g *Graph) GetAt(i int) *Graph

GetAt returns a subnode by index, or nil if the index is out of range.

func (*Graph) GetBool 

func (g *Graph) GetBool(path string) (bool, error)

GetBool returns the result of applying a path to the given Graph. The result is returned as a bool. If the path result cannot be converted to a boolean, then an error is returned.

func (*Graph) GetBytes 

func (g *Graph) GetBytes(path string) ([]byte, error)

GetBytes returns the result of applying a path to the given Graph. The result is returned as a byte slice.

func (*Graph) GetFloat64 

func (g *Graph) GetFloat64(path string) (float64, error)

GetFloat64 returns the result of applying a path to the given Graph. The result is returned as a float64. If the path result cannot be converted to a float, then an error is returned.

func (*Graph) GetInt64 

func (g *Graph) GetInt64(path string) (int64, error)

GetInt64 returns the result of applying a path to the given Graph. The result is returned as an int64. If the path result cannot be converted to an integer, then an error is returned.

func (*Graph) GetString 

func (g *Graph) GetString(path string) (string, error)

GetString returns the result of applying a path to the given Graph. The result is returned as a string. If the error information is not used, then this method is equivalent to Get(path).String()

func (*Graph) Int64 

func (g *Graph) Int64(def ...int64) int64

Int64 returns the node as an int64. If the node is not a number, it returns 0, or the default value if given.

func (*Graph) Interface 

func (g *Graph) Interface() interface{}

Interface returns the first child of this node as an interface

func (*Graph) JSON 

func (g *Graph) JSON() []byte

JSON produces JSON text from a Graph

JSON has maps (objects, {}), lists (arrays, []) and values.

Values can be strings, numbers, maps, lists, 'true', 'false' or 'null'

map ::= '{' string ':' value [',' string : value]* '}' list ::= '[' value [',' value]* ']'

By definition, since maps and lists cannot be distinguished in OGDL, any list should have a '_' root node. Any non-leaf node is a map (unless is contains '_', obviously).

func (*Graph) Len 

func (g *Graph) Len() int

Len returns the number of subnodes (outgoing edges, out degree) of this node.

func (*Graph) Node 

func (g *Graph) Node(s string) *Graph

Node returns the first subnode whose string value is equal to the given string. It returns nil if not found.

func (*Graph) Number 

func (g *Graph) Number() interface{}

Number returns either a float64, int64 or nil

func (*Graph) Process 

func (g *Graph) Process(ctx *Graph) []byte

Process processes the parsed template, returning the resulting text in a byte array. The variable parts are resolved out of the Graph given.

Example (For) 
g := FromString("spaces\n  cvm\n  req\n    stkreq\n    sysreq\n  design\n    hardware")
t := NewTemplate("$spaces\n$for(s,spaces)$s._string\n$for(d,s[0])- $d\n$end$end")
s := t.Process(g)

fmt.Println(string(s))

Output:

cvm
req
  stkreq
  sysreq
design
  hardware
cvm
req
- stkreq
- sysreq
design
- hardware

func (*Graph) Scalar 

func (g *Graph) Scalar() interface{}

Scalar returns the current node content, reducing the number of types following these rules: 

uint* -> int64
int*  -> int64
float* -> float64
byte -> int64
rune -> int64
bool -> bool
string, []byte: if it represents an int or float or bool,
  convert to int64, float64 or bool

Any other type is returned as is.

func (*Graph) Set 

func (g *Graph) Set(s string, val interface{}) *Graph

Set sets the first occurrence of the given path to the value given.

Example 
g := FromString("a b c")
g.Set("a.b", "d")

fmt.Println(g.Text())

Output:

a
  b
    d
Example (A) 
g := New(nil)

g.Add("R").Add("b")
r := g.Node("R")
r.Set("id", "1")

fmt.Println(g.Text())

Output:

R
  b
  id
    1
Example (Index) 
g := FromString("a b c")
g.Set("a[1]", "d")

fmt.Println(g.Text())

Output:

a
  b
    c
  d

func (*Graph) Show 

func (g *Graph) Show() string

Show prints the Graph as text including this (the top) node.

func (*Graph) String 

func (g *Graph) String(def ...string) string

String returns a string representation of this node, or an empty string. This function doesn't return an error, because it is mostly used in single variable return situations. String accepts one default value, which will be returned instead of an empty string.

func (*Graph) StringCSV 

func (g *Graph) StringCSV(def ...string) string

StringCSV returns a comma separated value representation of all direct subnodes. StringCSV accepts one default value, which will be returned instead of an empty string.

func (*Graph) Substitute 

func (g *Graph) Substitute(s string, v interface{})

Substitute traverses the graph substituting all nodes with content equal to s by v.

func (*Graph) Text 

func (g *Graph) Text() string

Text is the OGDL text emitter. It converts a Graph into OGDL text.

Strings are quoted if they contain spaces, newlines or special characters. Null elements are not printed, and act as transparent nodes.

func (*Graph) ThisBytes 

func (g *Graph) ThisBytes() []byte

ThisBytes returns the node as []byte, or nil if not possble.

func (*Graph) ThisFloat64 

func (g *Graph) ThisFloat64() (float64, bool)

ThisFloat64 returns a float64

func (*Graph) ThisInt64 

func (g *Graph) ThisInt64() (int64, bool)

ThisInt64 returns a int64 or nil

func (*Graph) ThisNumber 

func (g *Graph) ThisNumber() interface{}

ThisNumber returns either a float64, int64 or nil

func (*Graph) ThisScalar 

func (g *Graph) ThisScalar() interface{}

ThisScalar returns this node's content as an interface

func (*Graph) ThisString 

func (g *Graph) ThisString(def ...string) string

ThisString returns the current node content as a string

func (*Graph) ThisType 

func (g *Graph) ThisType() string

ThisType returns the name of the native type contained in the current node.

func (*Graph) ThisValue 

func (g *Graph) ThisValue() reflect.Value

ThisValue returns this node as a reflect.Value.

func (*Graph) Value 

func (g *Graph) Value() reflect.Value

Value returns the node as a reflect.Value.

type Lexer 

type Lexer struct {
	// contains filtered or unexported fields
}

Lexer implements buffering for an io.Reader object, with multiple byte unread operations allowed.

func NewLexer 

func NewLexer(rd io.Reader) *Lexer

NewLexer returns a new Lexer whose buffer has the default size.

func (*Lexer) Block 

func (p *Lexer) Block(nsp int) (string, bool)

Block ::= '\\' NL LINES_OF_TEXT

func (*Lexer) Break 

func (p *Lexer) Break() bool

Break (= newline) is NL, CR or CR+NL

func (*Lexer) Byte 

func (p *Lexer) Byte() (byte, error)

Byte reads and returns a single byte. If no byte is available, returns 0 and an error.

func (*Lexer) Comment 

func (p *Lexer) Comment() bool

Comment consumes anything from # up to the end of the line.

func (*Lexer) End 

func (p *Lexer) End() bool

End returns true if the end of stream has been reached.

func (*Lexer) Error 

func (p *Lexer) Error() error

func (*Lexer) Integer 

func (p *Lexer) Integer() (string, bool)

Integer returns true if it finds an (unsigned) integer at the current parser position. It returns also the number found.

func (*Lexer) Number 

func (p *Lexer) Number() (string, bool)

Number returns true if it finds a number at the current parser position. It returns also the number found. TODO recognize exp notation ?

func (*Lexer) Operator 

func (p *Lexer) Operator() (string, bool)

Operator returns true if it finds an operator at the current parser position It returns also the operator found.

func (*Lexer) PeekByte 

func (p *Lexer) PeekByte() byte

PeekByte returns the next byte witohut consuming it

func (*Lexer) PeekRune 

func (p *Lexer) PeekRune() (rune, error)

PeekRune returns the next rune witohut consuming it

func (*Lexer) Quoted 

func (p *Lexer) Quoted(ind int) (string, bool, error)

Quoted string. Can have newlines in it. It returns the string if any, a bool indicating if a quoted string was found, and a possible error.

func (*Lexer) Rune 

func (p *Lexer) Rune() (rune, error)

Rune reads a single UTF-8 encoded Unicode character and returns the rune. If the encoded rune is invalid, it consumes one byte and returns unicode.ReplacementChar (U+FFFD) with a size of 1.

func (*Lexer) Scalar 

func (p *Lexer) Scalar(n int) (string, bool)

Scalar ::= quoted | string

func (*Lexer) ScalarType 

func (p *Lexer) ScalarType(n int) (interface{}, bool)

ScalarType ::= string | int64 | float64 | bool

func (*Lexer) Space 

func (p *Lexer) Space() (int, byte)

Space is (0x20|0x09)+. It returns a boolean indicating if space has been found, and an integer indicating how many spaces, iff uniform (either all 0x20 or 0x09)

func (*Lexer) String 

func (p *Lexer) String() (string, bool)

String is a concatenation of characters that are > 0x20

func (*Lexer) StringStop 

func (p *Lexer) StringStop(stopBytes []byte) (string, bool)

StringStop is a concatenation of text bytes that are not in the parameter stopBytes

func (*Lexer) TemplateText 

func (p *Lexer) TemplateText() (string, bool)

TemplateText parses text in a template.

func (*Lexer) Token8 

func (p *Lexer) Token8() (string, bool)

Token8 reads from the Parser input stream and returns a token, if any. A token is defined as a sequence of Unicode letters and/or numbers and/or _.

func (*Lexer) UnreadByte 

func (p *Lexer) UnreadByte()

UnreadByte unreads the last byte. It can unread all buffered bytes.

func (*Lexer) UnreadRune 

func (p *Lexer) UnreadRune() error

UnreadRune unreads the last rune.

func (*Lexer) WhiteSpace 

func (p *Lexer) WhiteSpace() bool

WhiteSpace is equivalent to Space | Break. It consumes all white space, whether spaces, tabs or newlines

type Log 

type Log struct {
	// contains filtered or unexported fields
}

Log is a log store for binary OGDL objects.

All objects are appended to a file, and a position is returned.

func OpenLog 

func OpenLog(file string) (*Log, error)

OpenLog opens a log file. If the file doesn't exist, it is created.

func (*Log) Add 

func (log *Log) Add(g *Graph) int64

Add adds an OGDL object to the log. The starting position into the log is returned.

func (*Log) AddBinary 

func (log *Log) AddBinary(b []byte) int64

AddBinary adds an OGDL binary object to the log. The starting position into the log is returned.

func (*Log) Close 

func (log *Log) Close()

Close closes a log file

func (*Log) Get 

func (log *Log) Get(i int64) (*Graph, int64, error)

Get returns the OGDL object at the position given and the position of the next object, or an error.

func (*Log) GetBinary 

func (log *Log) GetBinary(i int64) ([]byte, int64, error)

GetBinary returns the OGDL object at the position given and the position of the next object, or an error. The object returned is in binary form, exactly as it is stored in the log.

func (*Log) Sync 

func (log *Log) Sync()

Sync commits the changes to disk (the exact behavior is OS dependent).

type Parser 

type Parser struct {
	Lexer // Buffered byte and rune readed
	// contains filtered or unexported fields
}

Parser embeds Lexer and holds some state

func NewBytesParser 

func NewBytesParser(buf []byte) *Parser

NewBytesParser returns a new Parser from a byte array

func NewParser 

func NewParser(rd io.Reader) *Parser

NewParser return a new Parser from a Reader

func NewStringParser 

func NewStringParser(s string) *Parser

NewStringParser returns a new Parser from a string

func (*Parser) ArgList 

func (p *Parser) ArgList() bool

ArgList ::= space? expression space? [, space? expression]* space?

arglist < stream > events

arglist can be empty, then returning false (this fact is not represented in the BNF definition).

func (*Parser) Args 

func (p *Parser) Args(dot bool) (bool, error)

Args ::= '(' space? sequence? space? ')'

func (*Parser) Dec 

func (p *Parser) Dec()

Dec decreses the event handler level by one

func (*Parser) Emit 

func (p *Parser) Emit(s string)

Emit outputs a string event at the current level. This will show up in the graph

func (*Parser) Expression 

func (p *Parser) Expression() bool

Expression := expr1 (op2 expr1)*

func (*Parser) Graph 

func (p *Parser) Graph() *Graph

Graph returns the parser tree

func (*Parser) Handler 

func (p *Parser) Handler() *SimpleEventHandler

Handler returns the event handler being used

func (*Parser) Inc 

func (p *Parser) Inc()

Inc increases the event handler level by one

func (*Parser) Index 

func (p *Parser) Index() bool

Index ::= '[' expression ']'

func (*Parser) Ogdl 

func (p *Parser) Ogdl()

Ogdl is the main function for parsing OGDL text.

An OGDL stream is a sequence of lines (a block of text or a quoted string can span multiple lines but is still parsed by Line()) 

Graph ::= Line* End

func (*Parser) OgdlTypes 

func (p *Parser) OgdlTypes()

OgdlTypes is the main function for parsing OGDL text.

This version tries to convert unquoted strings that can be parsed as ints, floats or bools to their corresponding type in Go (string | int64 | float64 | bool).

func (*Parser) Path 

func (p *Parser) Path() bool

Path parses an OGDL path, or an extended path as used in templates. 

path ::= element ('.' element)*

element ::= token | integer | quoted | group | index | selector

(Dot optional before Group, Index, Selector)

group := '(' Expression [[,] Expression]* ')'
index := '[' Expression ']'
selector := '{' Expression '}'

The OGDL parser doesn't need to know about Unicode. The character classification relies on values < 127, thus in the ASCII range, which is also part of Unicode.

Note: On the other hand it would be stupid not to recognize for example Unicode quotation marks if we know that we have UTF-8. But when do we know for sure?

func (*Parser) Selector 

func (p *Parser) Selector() bool

Selector ::= '{' expression? '}'

func (*Parser) Template 

func (p *Parser) Template()

Template ::= (Text | Variable)*

func (*Parser) Text 

func (p *Parser) Text() bool

Text returns the next text part of the template (until it finds a variable)

func (*Parser) UnaryExpression 

func (p *Parser) UnaryExpression() bool

UnaryExpression := cpath | constant | op1 cpath | op1 constant | '(' expr ')' | op1 '(' expr ')'

func (*Parser) Variable 

func (p *Parser) Variable() bool

Variable parses variables in a template. They begin with $.

type SimpleEventHandler 

type SimpleEventHandler struct {
	// contains filtered or unexported fields
}

SimpleEventHandler receives events and produces a tree.

func (*SimpleEventHandler) Add 

func (e *SimpleEventHandler) Add(s string)

Add creates a string node at the current level.

func (*SimpleEventHandler) AddAt 

func (e *SimpleEventHandler) AddAt(s string, lv int)

AddAt creates a string node at the specified level.

func (*SimpleEventHandler) AddBytes 

func (e *SimpleEventHandler) AddBytes(b []byte)

AddBytes creates a byte array node at the current level

func (*SimpleEventHandler) AddBytesAt 

func (e *SimpleEventHandler) AddBytesAt(b []byte, lv int)

AddBytesAt creates a byte array node at the specified level

func (*SimpleEventHandler) AddItf 

func (e *SimpleEventHandler) AddItf(i interface{})

AddItf creates a string node at the current level.

func (*SimpleEventHandler) Dec 

func (e *SimpleEventHandler) Dec()

Dec decrements the current level by 1.

func (*SimpleEventHandler) Delete 

func (e *SimpleEventHandler) Delete()

Delete removes the last node added

func (*SimpleEventHandler) Inc 

func (e *SimpleEventHandler) Inc()

Inc increments the current level by 1.

func (*SimpleEventHandler) Level 

func (e *SimpleEventHandler) Level() int

Level returns the current level

func (*SimpleEventHandler) SetLevel 

func (e *SimpleEventHandler) SetLevel(l int)

SetLevel sets the current level

func (*SimpleEventHandler) Tree 

func (e *SimpleEventHandler) Tree() *Graph

Tree returns the Graph object built from the events sent to this event handler.

Source Files

View all Source files

Directories

Path Synopsis
cmd
gpath
gpath <path> [file] Return the specified path from an OGDL file, or from stdin.
 gpath <path> [file] Return the specified path from an OGDL file, or from stdin.
gtemplate
gtemplate <template_file> [ogdl_file]* Processes a template file and solves variables in it using data from any of the OGDL files given
 gtemplate <template_file> [ogdl_file]* Processes a template file and solves variables in it using data from any of the OGDL files given
json2ogdl
json2ogdl [json_file]*
 json2ogdl [json_file]*
xml2ogdl
io
gxml

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