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Diffstat (limited to 'syntax.md')
| -rw-r--r-- | syntax.md | 36 |
1 files changed, 17 insertions, 19 deletions
@@ -1,10 +1,8 @@ ---- -title: Syntax ---- +# Syntax The syntax of Crowbar mostly matches the syntax of C, with fewer obscure/advanced/edge case features. -# Source Files +## Source Files A Crowbar source file is UTF-8. Crowbar source files can come in two varieties, an *implementation file* and a *header file*. @@ -12,7 +10,7 @@ An implementation file conventionally has a `.cro` extension, and a header file A Crowbar source file is read into memory in two phases: *scanning* (which converts text into an unstructured sequence of tokens) and *parsing* (which converts an unstructured sequence of tokens into a parse tree). -# Scanning +## Scanning A *token* is one of the following kinds of token: @@ -24,7 +22,7 @@ A *token* is one of the following kinds of token: Tokens are separated by either *whitespace* or a *comment*. -## Keywords +### Keywords A *keyword* is one of the following literal words: @@ -59,7 +57,7 @@ A *keyword* is one of the following literal words: - `void` - `while` -## Identifiers +### Identifiers An *identifier* is a sequence of one or more characters having Unicode categories within a legal set. @@ -80,7 +78,7 @@ Subsequent characters may have any of the above-listed Unicode categories, or on - `Nl` Letter Number (e.g. `Ⅳ`, U+2163 Roman Numeral Four) - `No` Other Number (e.g. `¼`, U+00BC Vulgar Fraction One Quarter) -## Constants +### Constants A *constant* can have one of six types: @@ -94,7 +92,7 @@ A *constant* can have one of six types: - or a `.` followed by a decimal constant followed by either an `e` or `E` followed by a decimal constant; - or a *character constant*, a `'` followed by either a single character or an *escape sequence* followed by another `'`. -### Escape Sequences +#### Escape Sequences The following sequences of characters are *escape sequences*: @@ -109,13 +107,13 @@ The following sequences of characters are *escape sequences*: - `\u` followed by four characters drawn from the set {`0`, `1`, `2`, `3`, `4`, `5`, `6`, `7`, `8`, `9`, `A`, `a`, `B`, `b`, `C`, `c`, `D`, `d`, `E`, `e`, `F`, `f`} - `\U` followed by eight characters drawn from the set {`0`, `1`, `2`, `3`, `4`, `5`, `6`, `7`, `8`, `9`, `A`, `a`, `B`, `b`, `C`, `c`, `D`, `d`, `E`, `e`, `F`, `f`} -## String Literals +### String Literals A *string literal* begins with a `"`. It then contains a sequence where each element is either an escape sequence or a character that is neither `"` nor `\`. It then ends with a `"`. -## Punctuators +### Punctuators The following sequences of characters form *punctuators*: @@ -161,11 +159,11 @@ The following sequences of characters form *punctuators*: - `|=` - `^=` -## Whitespace +### Whitespace A nonempty sequence of characters is considered to be *whitespace* if each character in it has a Unicode class of either Space Separator or Control Other. -## Comments +### Comments A *comment* can be either a *line comment* or a *block comment*. @@ -173,11 +171,11 @@ A *line comment* begins with the characters `//` if they occur outside of a stri A *block comment* begins with the characters `/*` if they occur outside of a string literal or comment, and ends with the characters `*/`. -# Parsing +## Parsing The syntax of Crowbar is given as a [parsing expression grammar](https://en.wikipedia.org/wiki/Parsing_expression_grammar): -## Entry points +### Entry points ``` HeaderFile ← HeaderFileElement+ @@ -190,7 +188,7 @@ ImplementationFileElement ← HeaderFileElement / FunctionDefinition ``` -## Top-level elements +### Top-level elements ``` IncludeStatement ← 'include' string-literal ';' @@ -211,7 +209,7 @@ SignatureArguments ← Type identifier ',' SignatureArguments / Type identifier ','? ``` -## Statements +### Statements ``` Block ← '{' Statement* '}' @@ -263,7 +261,7 @@ AssignmentStatementBody ← AssignmentTargetExpression '=' Expression / ExpressionStatement ← Expression ';' ``` -## Types +### Types ``` Type ← 'const' BasicType / @@ -288,7 +286,7 @@ IntegerType ← 'char' / 'long' ``` -## Expressions +### Expressions ``` AssignmentTargetExpression ← identifier ATEElementSuffix* |