class CodeRay::Scanners::Lua
Scanner for the Lua programming lanuage.
The language’s complete syntax is defined in the Lua manual, which is what this scanner tries to conform to.
Constants
- IDENT_KIND
Automatic token kind selection for normal words.
- KEYWORDS
Keywords used in Lua.
- PREDEFINED_CONSTANTS
Constants set by the Lua core.
- PREDEFINED_EXPRESSIONS
The expressions contained in this array are parts of Lua’s `basic' library. Although it’s not entirely necessary to load that library, it is highly recommended and one would have to provide own implementations of some of these expressions if one does not do so. They however aren’t keywords, neither are they constants, but nearly predefined, so they get tagged as `predefined' rather than anything else.
This list excludes values of form `_UPPERCASE' because the Lua manual requires such identifiers to be reserved by Lua anyway and they are highlighted directly accordingly, without the need for specific identifiers to be listed here.
Protected Instance Methods
CodeRay entry hook. Starts parsing.
# File lib/coderay/scanners/lua.rb, line 59 def scan_tokens(encoder, options) state = options[:state] || @state brace_depth = @brace_depth num_equals = nil until eos? case state when :initial if match = scan(/\-\-\[\=*\[/) #--[[ long (possibly multiline) comment ]] num_equals = match.count("=") # Number must match for comment end encoder.begin_group(:comment) encoder.text_token(match, :delimiter) state = :long_comment elsif match = scan(/--.*$/) # --Lua comment encoder.text_token(match, :comment) elsif match = scan(/\[=*\[/) # [[ long (possibly multiline) string ]] num_equals = match.count("=") # Number must match for comment end encoder.begin_group(:string) encoder.text_token(match, :delimiter) state = :long_string elsif match = scan(/::\s*[a-zA-Z_][a-zA-Z0-9_]+\s*::/) # ::goto_label:: encoder.text_token(match, :label) elsif match = scan(/_[A-Z]+/) # _UPPERCASE are names reserved for Lua encoder.text_token(match, :predefined) elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) # Normal letters (or letters followed by digits) kind = IDENT_KIND[match] # Extra highlighting for entities following certain keywords if kind == :keyword and match == "function" state = :function_expected elsif kind == :keyword and match == "goto" state = :goto_label_expected elsif kind == :keyword and match == "local" state = :local_var_expected end encoder.text_token(match, kind) elsif match = scan(/\{/) # Opening table brace { encoder.begin_group(:map) encoder.text_token(match, brace_depth >= 1 ? :inline_delimiter : :delimiter) brace_depth += 1 state = :map elsif match = scan(/\}/) # Closing table brace } if brace_depth == 1 brace_depth = 0 encoder.text_token(match, :delimiter) encoder.end_group(:map) elsif brace_depth == 0 # Mismatched brace encoder.text_token(match, :error) else brace_depth -= 1 encoder.text_token(match, :inline_delimiter) encoder.end_group(:map) state = :map end elsif match = scan(/["']/) # String delimiters " and ' encoder.begin_group(:string) encoder.text_token(match, :delimiter) start_delim = match state = :string # ↓Prefix hex number ←|→ decimal number elsif match = scan(/-? (?:0x\h* \. \h+ (?:p[+\-]?\d+)? | \d*\.\d+ (?:e[+\-]?\d+)?)/ix) # hexadecimal constants have no E power, decimal ones no P power encoder.text_token(match, :float) # ↓Prefix hex number ←|→ decimal number elsif match = scan(/-? (?:0x\h+ (?:p[+\-]?\d+)? | \d+ (?:e[+\-]?\d+)?)/ix) # hexadecimal constants have no E power, decimal ones no P power encoder.text_token(match, :integer) elsif match = scan(/[\+\-\*\/%^\#=~<>\(\)\[\]:;,] | \.(?!\d)/x) # Operators encoder.text_token(match, :operator) elsif match = scan(/\s+/) # Space encoder.text_token(match, :space) else # Invalid stuff. Note that Lua doesn’t accept multibyte chars outside of strings, hence these are also errors. encoder.text_token(getch, :error) end # It may be that we’re scanning a full-blown subexpression of a table # (tables can contain full expressions in parts). # If this is the case, return to :map scanning state. state = :map if state == :initial && brace_depth >= 1 when :function_expected if match = scan(/\(.*?\)/m) # x = function() # "Anonymous" function without explicit name encoder.text_token(match, :operator) state = :initial elsif match = scan(/[a-zA-Z_] (?:[a-zA-Z0-9_\.] (?!\.\d))* [\.\:]/x) # function tbl.subtbl.foo() | function tbl:foo() # Colon only allowed as last separator encoder.text_token(match, :ident) elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) # function foo() encoder.text_token(match, :function) state = :initial elsif match = scan(/\s+/) # Between the `function' keyword and the ident may be any amount of whitespace encoder.text_token(match, :space) else encoder.text_token(getch, :error) state = :initial end when :goto_label_expected if match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) encoder.text_token(match, :label) state = :initial elsif match = scan(/\s+/) # Between the `goto' keyword and the label may be any amount of whitespace encoder.text_token(match, :space) else encoder.text_token(getch, :error) end when :local_var_expected if match = scan(/function/) # local function ... encoder.text_token(match, :keyword) state = :function_expected elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) encoder.text_token(match, :local_variable) elsif match = scan(/,/) encoder.text_token(match, :operator) elsif match = scan(/\=/) encoder.text_token(match, :operator) # After encountering the equal sign, arbitrary expressions are # allowed again, so just return to the main state for further # parsing. state = :initial elsif match = scan(/\n/) encoder.text_token(match, :space) state = :initial elsif match = scan(/\s+/) encoder.text_token(match, :space) else encoder.text_token(getch, :error) end when :long_comment if match = scan(/.*?(?=\]={#{num_equals}}\])/m) encoder.text_token(match, :content) delim = scan(/\]={#{num_equals}}\]/) encoder.text_token(delim, :delimiter) else # No terminator found till EOF encoder.text_token(rest, :error) terminate end encoder.end_group(:comment) state = :initial when :long_string if match = scan(/.*?(?=\]={#{num_equals}}\])/m) # Long strings do not interpret any escape sequences encoder.text_token(match, :content) delim = scan(/\]={#{num_equals}}\]/) encoder.text_token(delim, :delimiter) else # No terminator found till EOF encoder.text_token(rest, :error) terminate end encoder.end_group(:string) state = :initial when :string if match = scan(/[^\#{start_delim}\n]+/) # Everything except \ and the start delimiter character is string content (newlines are only allowed if preceeded by \ or \z) encoder.text_token(match, :content) elsif match = scan(/\(?:['"abfnrtv\]|z\s*|x\h\h|\d{1,3}|\n)/m) encoder.text_token(match, :char) elsif match = scan(Regexp.compile(start_delim)) encoder.text_token(match, :delimiter) encoder.end_group(:string) state = :initial elsif match = scan(/\n/) # Lua forbids unescaped newlines in normal non-long strings encoder.text_token("\\n\n", :error) # Visually appealing error indicator--otherwise users may wonder whether the highlighter cannot highlight multine strings encoder.end_group(:string) state = :initial else encoder.text_token(getch, :error) end when :map if match = scan(/[,;]/) encoder.text_token(match, :operator) elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]* (?=\s*=)/x) encoder.text_token(match, :key) encoder.text_token(scan(/\s+/), :space) if check(/\s+/) encoder.text_token(scan(/\=/), :operator) state = :initial elsif match = scan(/\s+/m) encoder.text_token(match, :space) else # Note this clause doesn’t advance the scan pointer, it’s a kind of # "retry with other options" (the :initial state then of course # advances the pointer). state = :initial end else raise end end if options[:keep_state] @state = state end encoder.end_group :string if [:string].include? state brace_depth.times { encoder.end_group :map } encoder end
Scanner initialization.
# File lib/coderay/scanners/lua.rb, line 53 def setup @state = :initial @brace_depth = 0 end