public final class ExpressionParser
extends Object
implements ExpressionParserConstants

This parser's specification is in ExpressionParser.jj, which is read by JavaCC and transformed into ExpressionParser.java. To modify this parser, please edit ExpressionParser.jj. Do not edit ExpressionParser.java directly.

Important: Do not use outside of Soy code (treat as superpackage-private).

 This parser parses several related things: variables, data references, globals, expression lists,
 and expressions.

 A. Variable:
    + A dollar sign "$" followed by an identifier (no space between).

 B. Data reference:
    + The first part must be "$" followed by the first key name (no space between).
    + The first key name cannot be a number.
    + A variable will only have the first part. A data reference may have subsequent parts.
    + Subsequent parts may be:
       - A dot "." or question-dot "?." followed by a key name or array index (spaces between are
         allowed).
       - Brackets "[ ]" or question-brackets "?[ ]" with any expression inside the brackets (see
         below for definition of expression).
    + A special case is when the first key name is "ij". In this case, it's a reference to
      injected data, and the reference is considered to start from the second key (i.e. the second
      key actually becomes the first key in the parsed node).
    Examples:   $aaa   $ij.aaa   $aaa.bbb.0.ccc.12   $aaa[0]['bbb'].ccc   $aaa[$bbb + $ccc]

 C. Global:
    + One or more identifiers. If more than one, a dot "." is used to separate them.
    + Must not be preceded by a dollar sign "$".
    Examples:   AAA   aaa.bbb.CCC   a22.b88_

 D. Expression list:
    + A comma-separated list of one or more expressions (see below for definition of expression).
    Example:   $aaa, $bbb.ccc + 1, round(3.14)

 E. Expression:

    1. Data reference:
       + See above for definition.

    2. Global:
       + See above for definition.

    3. Null:   null

    4. Boolean:   false   true

    5. Integer:
       + No octal numbers.
       + Hex numbers have strict lower case "x" in "0x" and "A-F" or "a-f".
       Examples:   0   26   -729   0x1a2B

    6. Float:
       + Decimal numbers only.
       + Must have digits on both sides of decimal point.
       + Exponents have strict lower case "e".
       Examples:   0.0   3.14159   -20.0   6.03e23   -3e-3

    7. String:
       + Single quotes only.
       + Escape sequences:   \\   \'   \"   \n   \r   \t   \b   \f
       + Unicode escape:   \ u ####   (backslash, "u", four hex digits -- no spaces in between)
       Examples:   ''   'abc'   'blah bleh bluh'   'aa\\bb\'cc\ndd'

    8. List literal:
       + Delimited by brackets.
       Examples:   []   ['blah', 123, $foo]

    9. Map literal:
       + Delimited by brackets.
       + Empty map has a single colon within the brackets (to distinguish from empty list).
       + Keys must be strings (or expressions that will evaluate to strings).
       Examples:   [:]   ['aaa': 'blah', 'bbb': 123, $boo: $foo]

    10. Operators:
       + Parentheses can be used to override precedence rules:   ( )
       + Precedence 8:   - (unary)   not
       + Precedence 7:   *   /   %
       + Precedence 6:   +   - (binary)
       + Precedence 5:   <   >   <=   >=
       + Precedence 4:   ==   !=
       + Precedence 3:   and
       + Precedence 2:   or
       + Precedence 1:   ?: (binary)   ? : (ternary)

    11. Functions:
       + Function name, open parenthesis, optional expression list, close parenthesis.
       + The function name is one identifier.
       + See above for the definition of an expression list.
       Examples:   isFirst($item)   foo()   myFunction(2, 'aa')