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Diffstat (limited to 'lib/pure/strformat.nim')
| -rw-r--r-- | lib/pure/strformat.nim | 664 |
1 files changed, 396 insertions, 268 deletions
diff --git a/lib/pure/strformat.nim b/lib/pure/strformat.nim index ddf996e48..7d093ebb3 100644 --- a/lib/pure/strformat.nim +++ b/lib/pure/strformat.nim @@ -9,307 +9,325 @@ ##[ String `interpolation`:idx: / `format`:idx: inspired by -Python's ``f``-strings. +Python's f-strings. -``fmt`` vs. ``&`` -================= +# `fmt` vs. `&` -You can use either ``fmt`` or the unary ``&`` operator for formatting. The +You can use either `fmt` or the unary `&` operator for formatting. The difference between them is subtle but important. -The ``fmt"{expr}"`` syntax is more aesthetically pleasing, but it hides a small +The `fmt"{expr}"` syntax is more aesthetically pleasing, but it hides a small gotcha. The string is a `generalized raw string literal <manual.html#lexical-analysis-generalized-raw-string-literals>`_. This has some surprising effects: +]## -.. code-block:: nim - - import strformat - let msg = "hello" - doAssert fmt"{msg}\n" == "hello\\n" +runnableExamples: + let msg = "hello" + assert fmt"{msg}\n" == "hello\\n" -Because the literal is a raw string literal, the ``\n`` is not interpreted as +##[ +Because the literal is a raw string literal, the `\n` is not interpreted as an escape sequence. -There are multiple ways to get around this, including the use of the ``&`` -operator: - -.. code-block:: nim +There are multiple ways to get around this, including the use of the `&` operator: +]## - import strformat - let msg = "hello" +runnableExamples: + let msg = "hello" - doAssert &"{msg}\n" == "hello\n" + assert &"{msg}\n" == "hello\n" - doAssert fmt"{msg}{'\n'}" == "hello\n" - doAssert fmt("{msg}\n") == "hello\n" - doAssert "{msg}\n".fmt == "hello\n" + assert fmt"{msg}{'\n'}" == "hello\n" + assert fmt("{msg}\n") == "hello\n" + assert "{msg}\n".fmt == "hello\n" +##[ The choice of style is up to you. -Formatting strings -================== - -.. code-block:: nim - - import strformat - - doAssert &"""{"abc":>4}""" == " abc" - doAssert &"""{"abc":<4}""" == "abc " - -Formatting floats -================= +# Formatting strings +]## -.. code-block:: nim +runnableExamples: + assert &"""{"abc":>4}""" == " abc" + assert &"""{"abc":<4}""" == "abc " - import strformat - doAssert fmt"{-12345:08}" == "-0012345" - doAssert fmt"{-1:3}" == " -1" - doAssert fmt"{-1:03}" == "-01" - doAssert fmt"{16:#X}" == "0x10" +##[ +# Formatting floats +]## - doAssert fmt"{123.456}" == "123.456" - doAssert fmt"{123.456:>9.3f}" == " 123.456" - doAssert fmt"{123.456:9.3f}" == " 123.456" - doAssert fmt"{123.456:9.4f}" == " 123.4560" - doAssert fmt"{123.456:>9.0f}" == " 123." - doAssert fmt"{123.456:<9.4f}" == "123.4560 " +runnableExamples: + assert fmt"{-12345:08}" == "-0012345" + assert fmt"{-1:3}" == " -1" + assert fmt"{-1:03}" == "-01" + assert fmt"{16:#X}" == "0x10" - doAssert fmt"{123.456:e}" == "1.234560e+02" - doAssert fmt"{123.456:>13e}" == " 1.234560e+02" - doAssert fmt"{123.456:13e}" == " 1.234560e+02" + assert fmt"{123.456}" == "123.456" + assert fmt"{123.456:>9.3f}" == " 123.456" + assert fmt"{123.456:9.3f}" == " 123.456" + assert fmt"{123.456:9.4f}" == " 123.4560" + assert fmt"{123.456:>9.0f}" == " 123." + assert fmt"{123.456:<9.4f}" == "123.4560 " + assert fmt"{123.456:e}" == "1.234560e+02" + assert fmt"{123.456:>13e}" == " 1.234560e+02" + assert fmt"{123.456:13e}" == " 1.234560e+02" -Debugging strings -================= +##[ +# Expressions +]## +runnableExamples: + let x = 3.14 + assert fmt"{(if x!=0: 1.0/x else: 0):.5}" == "0.31847" + assert fmt"""{(block: + var res: string + for i in 1..15: + res.add (if i mod 15 == 0: "FizzBuzz" + elif i mod 5 == 0: "Buzz" + elif i mod 3 == 0: "Fizz" + else: $i) & " " + res)}""" == "1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz " +##[ +# Debugging strings -``fmt"{expr=}"`` expands to ``fmt"expr={expr}"`` namely the text of the expression, +`fmt"{expr=}"` expands to `fmt"expr={expr}"` namely the text of the expression, an equal sign and the results of evaluated expression. +]## -.. code-block:: nim - - import strformat - doAssert fmt"{123.456=}" == "123.456=123.456" - doAssert fmt"{123.456=:>9.3f}" == "123.456= 123.456" - - let x = "hello" - doAssert fmt"{x=}" == "x=hello" - doAssert fmt"{x =}" == "x =hello" +runnableExamples: + assert fmt"{123.456=}" == "123.456=123.456" + assert fmt"{123.456=:>9.3f}" == "123.456= 123.456" - let y = 3.1415926 - doAssert fmt"{y=:.2f}" == fmt"y={y:.2f}" - doAssert fmt"{y=}" == fmt"y={y}" - doAssert fmt"{y = : <8}" == fmt"y = 3.14159 " + let x = "hello" + assert fmt"{x=}" == "x=hello" + assert fmt"{x =}" == "x =hello" - proc hello(a: string, b: float): int = 12 - let a = "hello" - let b = 3.1415926 - doAssert fmt"{hello(x, y) = }" == "hello(x, y) = 12" - doAssert fmt"{x.hello(y) = }" == "x.hello(y) = 12" - doAssert fmt"{hello x, y = }" == "hello x, y = 12" + let y = 3.1415926 + assert fmt"{y=:.2f}" == fmt"y={y:.2f}" + assert fmt"{y=}" == fmt"y={y}" + assert fmt"{y = : <8}" == fmt"y = 3.14159 " + proc hello(a: string, b: float): int = 12 + assert fmt"{hello(x, y) = }" == "hello(x, y) = 12" + assert fmt"{x.hello(y) = }" == "x.hello(y) = 12" + assert fmt"{hello x, y = }" == "hello x, y = 12" +##[ Note that it is space sensitive: +]## -.. code-block:: nim - - import strformat - let x = "12" - doAssert fmt"{x=}" == "x=12" - doAssert fmt"{x =:}" == "x =12" - doAssert fmt"{x =}" == "x =12" - doAssert fmt"{x= :}" == "x= 12" - doAssert fmt"{x= }" == "x= 12" - doAssert fmt"{x = :}" == "x = 12" - doAssert fmt"{x = }" == "x = 12" - doAssert fmt"{x = :}" == "x = 12" - doAssert fmt"{x = }" == "x = 12" - +runnableExamples: + let x = "12" + assert fmt"{x=}" == "x=12" + assert fmt"{x =:}" == "x =12" + assert fmt"{x =}" == "x =12" + assert fmt"{x= :}" == "x= 12" + assert fmt"{x= }" == "x= 12" + assert fmt"{x = :}" == "x = 12" + assert fmt"{x = }" == "x = 12" + assert fmt"{x = :}" == "x = 12" + assert fmt"{x = }" == "x = 12" -Implementation details -====================== +##[ +# Implementation details -An expression like ``&"{key} is {value:arg} {{z}}"`` is transformed into: +An expression like `&"{key} is {value:arg} {{z}}"` is transformed into: -.. code-block:: nim + ```nim var temp = newStringOfCap(educatedCapGuess) - temp.formatValue key, "" - temp.add " is " - temp.formatValue value, arg - temp.add " {z}" + temp.formatValue(key, "") + temp.add(" is ") + temp.formatValue(value, arg) + temp.add(" {z}") temp + ``` Parts of the string that are enclosed in the curly braces are interpreted -as Nim code, to escape an ``{`` or ``}`` double it. +as Nim code. To escape a `{` or `}`, double it. + +Within a curly expression, however, `{`, `}`, must be escaped with a backslash. + +To enable evaluating Nim expressions within curlies, colons inside parentheses +do not need to be escaped. +]## + +runnableExamples: + let x = "hello" + assert fmt"""{ "\{(" & x & ")\}" }""" == "{(hello)}" + assert fmt"""{{({ x })}}""" == "{(hello)}" + assert fmt"""{ $(\{x:1,"world":2\}) }""" == """[("hello", 1), ("world", 2)]""" -``&`` delegates most of the work to an open overloaded set -of ``formatValue`` procs. The required signature for a type ``T`` that supports -formatting is usually ``proc formatValue(result: var string; x: T; specifier: string)``. +##[ +`&` delegates most of the work to an open overloaded set +of `formatValue` procs. The required signature for a type `T` that supports +formatting is usually `proc formatValue(result: var string; x: T; specifier: string)`. The subexpression after the colon -(``arg`` in ``&"{key} is {value:arg} {{z}}"``) is optional. It will be passed as -the last argument to ``formatValue``. When the colon with the subexpression it is +(`arg` in `&"{key} is {value:arg} {{z}}"`) is optional. It will be passed as +the last argument to `formatValue`. When the colon with the subexpression it is left out, an empty string will be taken instead. For strings and numeric types the optional argument is a so-called "standard format specifier". +# Standard format specifiers for strings, integers and floats -Standard format specifier for strings, integers and floats -========================================================== +The general form of a standard format specifier is: + [[fill]align][sign][#][0][minimumwidth][.precision][type] -The general form of a standard format specifier is:: +The square brackets `[]` indicate an optional element. - [[fill]align][sign][#][0][minimumwidth][.precision][type] +The optional `align` flag can be one of the following: -The square brackets ``[]`` indicate an optional element. - -The optional align flag can be one of the following: - -'<' - Forces the field to be left-aligned within the available +`<` +: Forces the field to be left-aligned within the available space. (This is the default for strings.) -'>' - Forces the field to be right-aligned within the available space. +`>` +: Forces the field to be right-aligned within the available space. (This is the default for numbers.) -'^' - Forces the field to be centered within the available space. +`^` +: Forces the field to be centered within the available space. Note that unless a minimum field width is defined, the field width will always be the same size as the data to fill it, so that the alignment option has no meaning in this case. -The optional 'fill' character defines the character to be used to pad +The optional `fill` character defines the character to be used to pad the field to the minimum width. The fill character, if present, must be followed by an alignment flag. -The 'sign' option is only valid for numeric types, and can be one of the following: +The `sign` option is only valid for numeric types, and can be one of the following: ================= ==================================================== Sign Meaning ================= ==================================================== -``+`` Indicates that a sign should be used for both +`+` Indicates that a sign should be used for both positive as well as negative numbers. -``-`` Indicates that a sign should be used only for +`-` Indicates that a sign should be used only for negative numbers (this is the default behavior). (space) Indicates that a leading space should be used on positive numbers. ================= ==================================================== -If the '#' character is present, integers use the 'alternate form' for formatting. -This means that binary, octal, and hexadecimal output will be prefixed -with '0b', '0o', and '0x', respectively. +If the `#` character is present, integers use the 'alternate form' for formatting. +This means that binary, octal and hexadecimal output will be prefixed +with `0b`, `0o` and `0x`, respectively. -'width' is a decimal integer defining the minimum field width. If not specified, +`width` is a decimal integer defining the minimum field width. If not specified, then the field width will be determined by the content. -If the width field is preceded by a zero ('0') character, this enables +If the width field is preceded by a zero (`0`) character, this enables zero-padding. -The 'precision' is a decimal number indicating how many digits should be displayed +The `precision` is a decimal number indicating how many digits should be displayed after the decimal point in a floating point conversion. For non-numeric types the field indicates the maximum field size - in other words, how many characters will be used from the field content. The precision is ignored for integer conversions. -Finally, the 'type' determines how the data should be presented. +Finally, the `type` determines how the data should be presented. The available integer presentation types are: - ================= ==================================================== Type Result ================= ==================================================== -``b`` Binary. Outputs the number in base 2. -``d`` Decimal Integer. Outputs the number in base 10. -``o`` Octal format. Outputs the number in base 8. -``x`` Hex format. Outputs the number in base 16, using +`b` Binary. Outputs the number in base 2. +`d` Decimal Integer. Outputs the number in base 10. +`o` Octal format. Outputs the number in base 8. +`x` Hex format. Outputs the number in base 16, using lower-case letters for the digits above 9. -``X`` Hex format. Outputs the number in base 16, using +`X` Hex format. Outputs the number in base 16, using uppercase letters for the digits above 9. -(None) the same as 'd' +(None) The same as `d`. ================= ==================================================== - The available floating point presentation types are: ================= ==================================================== Type Result ================= ==================================================== -``e`` Exponent notation. Prints the number in scientific - notation using the letter 'e' to indicate the +`e` Exponent notation. Prints the number in scientific + notation using the letter `e` to indicate the exponent. -``E`` Exponent notation. Same as 'e' except it converts +`E` Exponent notation. Same as `e` except it converts the number to uppercase. -``f`` Fixed point. Displays the number as a fixed-point +`f` Fixed point. Displays the number as a fixed-point number. -``F`` Fixed point. Same as 'f' except it converts the +`F` Fixed point. Same as `f` except it converts the number to uppercase. -``g`` General format. This prints the number as a +`g` General format. This prints the number as a fixed-point number, unless the number is too - large, in which case it switches to 'e' + large, in which case it switches to `e` exponent notation. -``G`` General format. Same as 'g' except switches to 'E' +`G` General format. Same as `g` except it switches to `E` if the number gets to large. -(None) similar to 'g', except that it prints at least one +`i` Complex General format. This is only supported for + complex numbers, which it prints using the mathematical + (RE+IMj) format. The real and imaginary parts are printed + using the general format `g` by default, but it is + possible to combine this format with one of the other + formats (e.g `jf`). +(None) Similar to `g`, except that it prints at least one digit after the decimal point. ================= ==================================================== - -Limitations -=========== +# Limitations Because of the well defined order how templates and macros are expanded, strformat cannot expand template arguments: -.. code-block:: nim + ```nim template myTemplate(arg: untyped): untyped = echo "arg is: ", arg echo &"--- {arg} ---" let x = "abc" myTemplate(x) + ``` -First the template ``myTemplate`` is expanded, where every identifier -``arg`` is substituted with its argument. The ``arg`` inside the +First the template `myTemplate` is expanded, where every identifier +`arg` is substituted with its argument. The `arg` inside the format string is not seen by this process, because it is part of a quoted string literal. It is not an identifier yet. Then the strformat -macro creates the ``arg`` identifier from the string literal. An +macro creates the `arg` identifier from the string literal, an identifier that cannot be resolved anymore. The workaround for this is to bind the template argument to a new local variable. -.. code-block:: nim - + ```nim template myTemplate(arg: untyped): untyped = block: let arg1 {.inject.} = arg echo "arg is: ", arg1 echo &"--- {arg1} ---" + ``` -The use of ``{.inject.}`` here is necessary again because of template +The use of `{.inject.}` here is necessary again because of template expansion order and hygienic templates. But since we generally want to -keep the hygienicness of ``myTemplate``, and we do not want ``arg1`` -to be injected into the context where ``myTemplate`` is expanded, -everything is wrapped in a ``block``. +keep the hygiene of `myTemplate`, and we do not want `arg1` +to be injected into the context where `myTemplate` is expanded, +everything is wrapped in a `block`. -Future directions -================= +# Future directions -A curly expression with commas in it like ``{x, argA, argB}`` could be -transformed to ``formatValue(result, x, argA, argB)`` in order to support +A curly expression with commas in it like `{x, argA, argB}` could be +transformed to `formatValue(result, x, argA, argB)` in order to support formatters that do not need to parse a custom language within a custom -language but instead prefer to use Nim's existing syntax. This also -helps in readability since there is only so much you can cram into +language but instead prefer to use Nim's existing syntax. This would also +help with readability, since there is only so much you can cram into single letter DSLs. - ]## -import macros, parseutils, unicode -import strutils except format +import std/[macros, parseutils, unicode] +import std/strutils except format + +when defined(nimPreviewSlimSystem): + import std/assertions + proc mkDigit(v: int, typ: char): string {.inline.} = assert(v < 26) @@ -318,10 +336,9 @@ proc mkDigit(v: int, typ: char): string {.inline.} = else: result = $chr(ord(if typ == 'x': 'a' else: 'A') + v - 10) -proc alignString*(s: string, minimumWidth: int; align = '\0'; - fill = ' '): string = - ## Aligns ``s`` using ``fill`` char. - ## This is only of interest if you want to write a custom ``format`` proc that +proc alignString*(s: string, minimumWidth: int; align = '\0'; fill = ' '): string = + ## Aligns `s` using the `fill` char. + ## This is only of interest if you want to write a custom `format` proc that ## should support the standard format specifiers. if minimumWidth == 0: result = s @@ -343,28 +360,30 @@ type fill*, align*: char ## Desired fill and alignment. sign*: char ## Desired sign. alternateForm*: bool ## Whether to prefix binary, octal and hex numbers - ## with ``0b``, ``0o``, ``0x``. + ## with `0b`, `0o`, `0x`. padWithZero*: bool ## Whether to pad with zeros rather than spaces. minimumWidth*, precision*: int ## Desired minimum width and precision. typ*: char ## Type like 'f', 'g' or 'd'. endPosition*: int ## End position in the format specifier after - ## ``parseStandardFormatSpecifier`` returned. - -proc formatInt(n: SomeNumber; radix: int; - spec: StandardFormatSpecifier): string = - ## Converts ``n`` to string. If ``n`` is `SomeFloat`, it casts to `int64`. - ## Conversion is done using ``radix``. If result's length is lesser than - ## ``minimumWidth``, it aligns result to the right or left (depending on ``a``) - ## with ``fill`` char. + ## `parseStandardFormatSpecifier` returned. + +proc formatInt(n: SomeNumber; radix: int; spec: StandardFormatSpecifier): string = + ## Converts `n` to a string. If `n` is `SomeFloat`, it casts to `int64`. + ## Conversion is done using `radix`. If result's length is less than + ## `minimumWidth`, it aligns result to the right or left (depending on `a`) + ## with the `fill` char. when n is SomeUnsignedInt: var v = n.uint64 let negative = false else: - var v = n.int64 - let negative = v.int64 < 0 - if negative: - # FIXME: overflow error for low(int64) - v = v * -1 + let n = n.int64 + let negative = n < 0 + var v = + if negative: + # `uint64(-n)`, but accounts for `n == low(int64)` + uint64(not n) + 1 + else: + uint64(n) var xx = "" if spec.alternateForm: @@ -379,9 +398,9 @@ proc formatInt(n: SomeNumber; radix: int; result = "0" else: result = "" - while v > type(v)(0): - let d = v mod type(v)(radix) - v = v div type(v)(radix) + while v > typeof(v)(0): + let d = v mod typeof(v)(radix) + v = v div typeof(v)(radix) result.add(mkDigit(d.int, spec.typ)) for idx in 0..<(result.len div 2): swap result[idx], result[result.len - idx - 1] @@ -413,13 +432,13 @@ proc formatInt(n: SomeNumber; radix: int; proc parseStandardFormatSpecifier*(s: string; start = 0; ignoreUnknownSuffix = false): StandardFormatSpecifier = ## An exported helper proc that parses the "standard format specifiers", - ## as specified by the grammar:: + ## as specified by the grammar: ## - ## [[fill]align][sign][#][0][minimumwidth][.precision][type] + ## [[fill]align][sign][#][0][minimumwidth][.precision][type] ## - ## This is only of interest if you want to write a custom ``format`` proc that - ## should support the standard format specifiers. If ``ignoreUnknownSuffix`` is true, - ## an unknown suffix after the ``type`` field is not an error. + ## This is only of interest if you want to write a custom `format` proc that + ## should support the standard format specifiers. If `ignoreUnknownSuffix` is true, + ## an unknown suffix after the `type` field is not an error. const alignChars = {'<', '>', '^'} result.fill = ' ' result.align = '\0' @@ -441,7 +460,7 @@ proc parseStandardFormatSpecifier*(s: string; start = 0; result.alternateForm = true inc i - if i+1 < s.len and s[i] == '0' and s[i+1] in {'0'..'9'}: + if i + 1 < s.len and s[i] == '0' and s[i+1] in {'0'..'9'}: result.padWithZero = true inc i @@ -462,50 +481,48 @@ proc parseStandardFormatSpecifier*(s: string; start = 0; raise newException(ValueError, "invalid format string, cannot parse: " & s[i..^1]) +proc toRadix(typ: char): int = + case typ + of 'x', 'X': 16 + of 'd', '\0': 10 + of 'o': 8 + of 'b': 2 + else: + raise newException(ValueError, + "invalid type in format string for number, expected one " & + " of 'x', 'X', 'b', 'd', 'o' but got: " & typ) + proc formatValue*[T: SomeInteger](result: var string; value: T; - specifier: string) = - ## Standard format implementation for ``SomeInteger``. It makes little + specifier: static string) = + ## Standard format implementation for `SomeInteger`. It makes little ## sense to call this directly, but it is required to exist - ## by the ``&`` macro. - if specifier.len == 0: + ## by the `&` macro. + when specifier.len == 0: result.add $value - return - let spec = parseStandardFormatSpecifier(specifier) - var radix = 10 - case spec.typ - of 'x', 'X': radix = 16 - of 'd', '\0': discard - of 'b': radix = 2 - of 'o': radix = 8 else: - raise newException(ValueError, - "invalid type in format string for number, expected one " & - " of 'x', 'X', 'b', 'd', 'o' but got: " & spec.typ) - result.add formatInt(value, radix, spec) + const + spec = parseStandardFormatSpecifier(specifier) + radix = toRadix(spec.typ) -proc formatValue*(result: var string; value: SomeFloat; specifier: string) = - ## Standard format implementation for ``SomeFloat``. It makes little + result.add formatInt(value, radix, spec) + +proc formatValue*[T: SomeInteger](result: var string; value: T; + specifier: string) = + ## Standard format implementation for `SomeInteger`. It makes little ## sense to call this directly, but it is required to exist - ## by the ``&`` macro. + ## by the `&` macro. if specifier.len == 0: result.add $value - return - let spec = parseStandardFormatSpecifier(specifier) - - var fmode = ffDefault - case spec.typ - of 'e', 'E': - fmode = ffScientific - of 'f', 'F': - fmode = ffDecimal - of 'g', 'G': - fmode = ffDefault - of '\0': discard else: - raise newException(ValueError, - "invalid type in format string for number, expected one " & - " of 'e', 'E', 'f', 'F', 'g', 'G' but got: " & spec.typ) + let + spec = parseStandardFormatSpecifier(specifier) + radix = toRadix(spec.typ) + result.add formatInt(value, radix, spec) + +proc formatFloat( + result: var string, value: SomeFloat, fmode: FloatFormatMode, + spec: StandardFormatSpecifier) = var f = formatBiggestFloat(value, fmode, spec.precision) var sign = false if value >= 0.0: @@ -540,25 +557,84 @@ proc formatValue*(result: var string; value: SomeFloat; specifier: string) = else: result.add res +proc toFloatFormatMode(typ: char): FloatFormatMode = + case typ + of 'e', 'E': ffScientific + of 'f', 'F': ffDecimal + of 'g', 'G': ffDefault + of '\0': ffDefault + else: + raise newException(ValueError, + "invalid type in format string for number, expected one " & + " of 'e', 'E', 'f', 'F', 'g', 'G' but got: " & typ) + +proc formatValue*(result: var string; value: SomeFloat; specifier: static string) = + ## Standard format implementation for `SomeFloat`. It makes little + ## sense to call this directly, but it is required to exist + ## by the `&` macro. + when specifier.len == 0: + result.add $value + else: + const + spec = parseStandardFormatSpecifier(specifier) + fmode = toFloatFormatMode(spec.typ) + + formatFloat(result, value, fmode, spec) + +proc formatValue*(result: var string; value: SomeFloat; specifier: string) = + ## Standard format implementation for `SomeFloat`. It makes little + ## sense to call this directly, but it is required to exist + ## by the `&` macro. + if specifier.len == 0: + result.add $value + else: + let + spec = parseStandardFormatSpecifier(specifier) + fmode = toFloatFormatMode(spec.typ) + + formatFloat(result, value, fmode, spec) + +proc formatValue*(result: var string; value: string; specifier: static string) = + ## Standard format implementation for `string`. It makes little + ## sense to call this directly, but it is required to exist + ## by the `&` macro. + const spec = parseStandardFormatSpecifier(specifier) + var value = + when spec.typ in {'s', '\0'}: value + else: static: + raise newException(ValueError, + "invalid type in format string for string, expected 's', but got " & + spec.typ) + when spec.precision != -1: + if spec.precision < runeLen(value): + const precision = cast[Natural](spec.precision) + setLen(value, Natural(runeOffset(value, precision))) + + result.add alignString(value, spec.minimumWidth, spec.align, spec.fill) + proc formatValue*(result: var string; value: string; specifier: string) = - ## Standard format implementation for ``string``. It makes little + ## Standard format implementation for `string`. It makes little ## sense to call this directly, but it is required to exist - ## by the ``&`` macro. + ## by the `&` macro. let spec = parseStandardFormatSpecifier(specifier) - var value = value - case spec.typ - of 's', '\0': discard - else: - raise newException(ValueError, - "invalid type in format string for string, expected 's', but got " & - spec.typ) + var value = + if spec.typ in {'s', '\0'}: value + else: + raise newException(ValueError, + "invalid type in format string for string, expected 's', but got " & + spec.typ) if spec.precision != -1: if spec.precision < runeLen(value): - setLen(value, runeOffset(value, spec.precision)) + let precision = cast[Natural](spec.precision) + setLen(value, Natural(runeOffset(value, precision))) + result.add alignString(value, spec.minimumWidth, spec.align, spec.fill) -proc formatValue[T: not SomeInteger](result: var string; value: T; - specifier: string) = +proc formatValue[T: not SomeInteger](result: var string; value: T; specifier: static string) = + mixin `$` + formatValue(result, $value, specifier) + +proc formatValue[T: not SomeInteger](result: var string; value: T; specifier: string) = mixin `$` formatValue(result, $value, specifier) @@ -568,19 +644,20 @@ template formatValue(result: var string; value: char; specifier: string) = template formatValue(result: var string; value: cstring; specifier: string) = result.add value -proc strformatImpl(pattern: NimNode; openChar, closeChar: char): NimNode = - if pattern.kind notin {nnkStrLit..nnkTripleStrLit}: - error "string formatting (fmt(), &) only works with string literals", pattern +proc strformatImpl(f: string; openChar, closeChar: char, + lineInfoNode: NimNode = nil): NimNode = + template missingCloseChar = + error("invalid format string: missing closing character '" & closeChar & "'") + if openChar == ':' or closeChar == ':': error "openChar and closeChar must not be ':'" - let f = pattern.strVal var i = 0 let res = genSym(nskVar, "fmtRes") - result = newNimNode(nnkStmtListExpr, lineInfoFrom = pattern) + result = newNimNode(nnkStmtListExpr, lineInfoNode) # XXX: https://github.com/nim-lang/Nim/issues/8405 # When compiling with -d:useNimRtl, certain procs such as `count` from the strutils # module are not accessible at compile-time: - let expectedGrowth = when defined(useNimRtl): 0 else: count(f, '{') * 10 + let expectedGrowth = when defined(useNimRtl): 0 else: count(f, openChar) * 10 result.add newVarStmt(res, newCall(bindSym"newStringOfCap", newLit(f.len + expectedGrowth))) var strlit = "" @@ -596,28 +673,46 @@ proc strformatImpl(pattern: NimNode; openChar, closeChar: char): NimNode = strlit = "" var subexpr = "" - while i < f.len and f[i] != closeChar and f[i] != ':': - if f[i] == '=': + var inParens = 0 + var inSingleQuotes = false + var inDoubleQuotes = false + template notEscaped:bool = f[i-1]!='\\' + while i < f.len and f[i] != closeChar and (f[i] != ':' or inParens != 0): + case f[i] + of '\\': + if i < f.len-1 and f[i+1] in {openChar,closeChar,':'}: inc i + of '\'': + if not inDoubleQuotes and notEscaped: inSingleQuotes = not inSingleQuotes + of '\"': + if notEscaped: inDoubleQuotes = not inDoubleQuotes + of '(': + if not (inSingleQuotes or inDoubleQuotes): inc inParens + of ')': + if not (inSingleQuotes or inDoubleQuotes): dec inParens + of '=': let start = i inc i i += f.skipWhitespace(i) + if i == f.len: + missingCloseChar if f[i] == closeChar or f[i] == ':': result.add newCall(bindSym"add", res, newLit(subexpr & f[start ..< i])) else: subexpr.add f[start ..< i] - else: - subexpr.add f[i] - inc i + continue + else: discard + subexpr.add f[i] + inc i + + if i == f.len: + missingCloseChar var x: NimNode try: x = parseExpr(subexpr) - except ValueError: - when declared(getCurrentExceptionMsg): - let msg = getCurrentExceptionMsg() - error("could not parse `" & subexpr & "`.\n" & msg, pattern) - else: - error("could not parse `" & subexpr & "`.\n", pattern) + except ValueError as e: + error("could not parse `$#` in `$#`.\n$#" % [subexpr, f, e.msg]) + x.copyLineInfo(lineInfoNode) let formatSym = bindSym("formatValue", brOpen) var options = "" if f[i] == ':': @@ -625,38 +720,71 @@ proc strformatImpl(pattern: NimNode; openChar, closeChar: char): NimNode = while i < f.len and f[i] != closeChar: options.add f[i] inc i + if i == f.len: + missingCloseChar if f[i] == closeChar: inc i - else: - doAssert false, "invalid format string: missing '}'" result.add newCall(formatSym, res, x, newLit(options)) elif f[i] == closeChar: - if f[i+1] == closeChar: + if i<f.len-1 and f[i+1] == closeChar: strlit.add closeChar inc i, 2 else: - doAssert false, "invalid format string: '}' instead of '}}'" - inc i + raiseAssert "invalid format string: '$1' instead of '$1$1'" % $closeChar else: strlit.add f[i] inc i if strlit.len > 0: result.add newCall(bindSym"add", res, newLit(strlit)) result.add res + # workaround for #20381 + var blockExpr = newNimNode(nnkBlockExpr, lineInfoNode) + blockExpr.add(newEmptyNode()) + blockExpr.add(result) + result = blockExpr when defined(debugFmtDsl): echo repr result -macro `&`*(pattern: string): untyped = strformatImpl(pattern, '{', '}') - ## For a specification of the ``&`` macro, see the module level documentation. +macro fmt(pattern: static string; openChar: static char, closeChar: static char, lineInfoNode: untyped): string = + ## version of `fmt` with dummy untyped param for line info + strformatImpl(pattern, openChar, closeChar, lineInfoNode) -macro fmt*(pattern: string): untyped = strformatImpl(pattern, '{', '}') - ## An alias for ``&``. +when not defined(nimHasCallsitePragma): + {.pragma: callsite.} -macro fmt*(pattern: string; openChar, closeChar: char): untyped = - ## Use ``openChar`` instead of '{' and ``closeChar`` instead of '}' +template fmt*(pattern: static string; openChar: static char, closeChar: static char): string {.callsite.} = + ## Interpolates `pattern` using symbols in scope. + runnableExamples: + let x = 7 + assert "var is {x * 2}".fmt == "var is 14" + assert "var is {{x}}".fmt == "var is {x}" # escape via doubling + const s = "foo: {x}" + assert s.fmt == "foo: 7" # also works with const strings + + assert fmt"\n" == r"\n" # raw string literal + assert "\n".fmt == "\n" # regular literal (likewise with `fmt("\n")` or `fmt "\n"`) + runnableExamples: + # custom `openChar`, `closeChar` + let x = 7 + assert "<x>".fmt('<', '>') == "7" + assert "<<<x>>>".fmt('<', '>') == "<7>" + assert "`x`".fmt('`', '`') == "7" + fmt(pattern, openChar, closeChar, dummyForLineInfo) + +template fmt*(pattern: static string): untyped {.callsite.} = + ## Alias for `fmt(pattern, '{', '}')`. + fmt(pattern, '{', '}', dummyForLineInfo) + +template `&`*(pattern: string{lit}): string {.callsite.} = + ## `&pattern` is the same as `pattern.fmt`. + ## For a specification of the `&` macro, see the module level documentation. + # pending bug #18275, bug #18278, use `pattern: static string` + # consider deprecating this, it's redundant with `fmt` and `fmt` is strictly + # more flexible, readable (no confusion with the binary `&`), self-documenting, + # not to mention #18275, bug #18278. runnableExamples: - let testInt = 123 - doAssert "<testInt>".fmt('<', '>') == "123" - doAssert """(()"foo" & "bar"())""".fmt(')', '(') == "(foobar)" - doAssert """ ""{"123+123"}"" """.fmt('"', '"') == " \"{246}\" " - strformatImpl(pattern, openChar.intVal.char, closeChar.intVal.char) + let x = 7 + assert &"{x}\n" == "7\n" # regular string literal + assert &"{x}\n" == "{x}\n".fmt # `fmt` can be used instead + assert &"{x}\n" != fmt"{x}\n" # see `fmt` docs, this would use a raw string literal + fmt(pattern, '{', '}', dummyForLineInfo) |