PSql.Deploy

2.0.0-pre05

Commands/Read-SqlMigration.ps1

using namespace System.Collections.Generic
using namespace System.Text

<#
    Copyright 2021 Jeffrey Sharp

    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#>

$ChunksRe = [regex] '(?mnsx)
    # m: ^/$ match BOL/EOL
    # n: named captures only
    # s: . includes \n
    # x: ignore pattern whitespace

    # Start where previous match ended
    \G

    # Match a chunk of SQL text
    (?<text>
        ( [^''\[/-] # regular character
        | '' ( [^''] | '''' )* ( '' | \z ) # string
        | \[ ( [^\]] | \]\] )* ( \] | \z ) # quoted identifier
        | -- (?!\#) .*? ( \r?\n | \z ) # line comment (non-magic)
        | - (?! -) # just a dash
        | / \* .*? ( \* / | \z ) # block comment
        | / (?!\*) # just a slash
        )*
    )

    # Match a magic comment or end of file
    (?<magic>
        ( ^ --\# (?<cmd> .*? ) ( \r?\n | \z ) # magic comment
        | \z # end of file
        )
    )
'

$CommandRe = [regex] '(?nsx)
    \A [\x20\t]* # beginning of string
    (?<name> \w+ ) [\x20\t]* # NAME
    (
        ( : [\x20\t]* ) # NAME:
        ( (?<args> [^\x20\t]+ ) [\x20\t]* )* # NAME: ARG ARG ARG
    )?
    \z # end of string
'

function Read-SqlMigration {
    [CmdletBinding()]
    param (
        # Path of the migration's main SQL file.
        [string] $Path
    )

    $Comparer = [StringComparer]::OrdinalIgnoreCase
    $Depends  = New-Object SortedSet[string] $Comparer
    $PreSql   = New-Object StringBuilder 4096
    $CoreSql  = New-Object StringBuilder 4096
    $PostSql  = New-Object StringBuilder 4096

    # Convert to absolute path
    $Path = Convert-Path -LiteralPath $Path

    # Decide the initial phase
    $Current  = switch ($Path | Split-Path | Split-Path -Leaf) {
        _Begin  { $PreSql  }
        _End    { $PostSql }
        default { $CoreSql }
    }

    # Parse into batches
    $Batches = Get-Content -LiteralPath $Path -Raw -Encoding UTF8 `
        | PSql\Expand-SqlCmdDirectives -Define @{ Path = Split-Path $Path } 

    foreach ($Batch in $Batches) {
        # Re-add batch separator if current phase had a previous batch
        if ($Current.Length -gt 0) {
            [void] $Current.AppendLine("GO")
        }

        # Parse batch into chunks
        foreach ($Chunk in $ChunksRe.Matches($Batch)) {
            $Text  = $Chunk.Groups['text' ].Value
            $Magic = $Chunk.Groups['magic'].Value

            # Text chunk belongs to block in progress
            [void] $Current.Append($Text)

            # Detect EOF
            if (-not $Magic) { break }

            # Split magic comment, if any
            $Match = $CommandRe.Match($Chunk.Groups['cmd'].Value)
            $Name  =   $Match.Groups['name'].Value
            $Argz  = @($Match.Groups['args'].Captures | ForEach-Object Value)

            # Interpret magic comment, if any
            switch ($Name) {
                PRE      { $Current = $PreSql  }
                CORE     { $Current = $CoreSql }
                OFFLINE  { $Current = $CoreSql }
                POST     { $Current = $PostSql }
                REQUIRES { [void] $Depends.Add($Argz) }
                default  { [void] $Current.Append($Magic) } # Not our magic
            }
        }
    }

    # Return a migration object
    [pscustomobject] @{
        Depends = $Depends
        PreSql  = $PreSql.ToString()
        CoreSql = $CoreSql.ToString()
        PostSql = $PostSql.ToString()
    }
}