water.rapids

Class Rapids

java.lang.Object

water.rapids.Rapids

public class Rapids
extends java.lang.Object

Rapids is an interpreter of abstract syntax trees.

This file contains the AST parser and parser helper functions. AST Execution starts in the ASTExec file, but spreads throughout Rapids.

Trees have a Lisp-like structure with the following "reserved" special characters:

'('

a nested function application expression till ')'

'{'

a nested function definition expression till '}'

'#'

a double: attached_token

'['

a numeric or string list expression, till ']'

'%'

an ID: attached_token

'"'

a String (double quote): attached_token

"'"

a String (single quote): attached_token

digits:

a double

letters or other specials:

an ID

In the above, attached_token signals that the special char has extra chars that must be parsed separately. These are variable names (in the case of %), doubles (in the case of #), Strings (in the case of ' and "), or number lists (in the case of '[' till ']').

Variables are lexically scoped inside 'let' expressions or at the top-level looked-up in the DKV directly (and must refer to a known type that is valid on the execution stack).

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	_str
protected int	_x

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Rapids(java.lang.String rapidsStr) Primary constructor

Method Summary

Methods

Modifier and Type	Method and Description
static Val	exec(java.lang.String rapids) Execute a single rapids call in a short-lived session
static Val	exec(java.lang.String rapids, Session ses) Compute and return a value in this session.
AST	parse() Parse an expression '(' a nested function application expression ') '{' a nested function definition expression '}' '#' a double: attached_token '[' a numeric list expression, till ']' '"' a String (double quote): attached_token "'" a String (single quote): attached_token digits: a double letters or other specials: an ID
static AST	parse(java.lang.String rapids) Parse a Rapids expression string into an Abstract Syntax Tree object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_str

protected final java.lang.String _str

_x

protected int _x

Constructor Detail

Rapids

protected Rapids(java.lang.String rapidsStr)

Primary constructor

Parameters:

rapidsStr - String containing a Rapids expression.

Method Detail

parse

public static AST parse(java.lang.String rapids)

Parse a Rapids expression string into an Abstract Syntax Tree object.

Parameters:

rapids - expression to parse

exec

public static Val exec(java.lang.String rapids)

Execute a single rapids call in a short-lived session

Parameters:

rapids - expression to parse

exec

public static Val exec(java.lang.String rapids,
       Session ses)

Compute and return a value in this session. Any returned frame shares Vecs with the session (is not deep copied), and so must be deleted by the caller (with a Rapids "rm" call) or will disappear on session exit, or is a normal global frame.

Parameters:

rapids - expression to parse

parse

public AST parse()

Parse an expression '(' a nested function application expression ') '{' a nested function definition expression '}' '#' a double: attached_token '[' a numeric list expression, till ']' '"' a String (double quote): attached_token "'" a String (single quote): attached_token digits: a double letters or other specials: an ID