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 AstRoot parser and parser helper functions. AstRoot 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).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Rapids.IllegalASTException

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 session) Compute and return a value in this session.
static boolean	isQuote(char c)
java.lang.String	match(char c)
double	number()
AstRoot	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 AstRoot	parse(java.lang.String rapids) Parse a Rapids expression string into an Abstract Syntax Tree object.
char	skipWS()
AstRoot	throwErr(java.lang.String msg)
java.lang.String	token()
Rapids	xpeek(char c)

Methods inherited from class java.lang.Object

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

Constructor Detail

Rapids

protected Rapids(java.lang.String rapidsStr)

Primary constructor

Parameters:

rapidsStr - String containing a Rapids expression.

Method Detail

parse

public static AstRoot 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 session)

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 AstRoot 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

xpeek

public Rapids xpeek(char c)

skipWS

public char skipWS()

token

public java.lang.String token()

number

public double number()

match

public java.lang.String match(char c)

isQuote

public static boolean isQuote(char c)

throwErr

public AstRoot throwErr(java.lang.String msg)